Screening transmissions for power level and object identifier in asset monitoring and tracking systems

ABSTRACT

A method for communicating to a recipient transceiver from a plurality of transceivers located within the broadcast range of the recipient transceiver includes: transmitting a communication at a first power level such that only a first group of transceivers receive the broadcast, the communication including a command causing each of the first group of transceivers not to respond to a subsequent broadcast; and subsequent thereto, transmitting a communication at a second power level greater than the first power level such that a second group of transceivers greater than and including the first group of transceivers receive the broadcast, but such that only a limited number of transceivers of the second group respond to the broadcast, the limited number of transceivers excluding the first group of transceivers. Each of the plurality of transceivers is associated with a respective sensor for acquiring data and transmitting the data to the recipient transceiver.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims all priority benefits under 35 U.S.C.§119 and §120 to the following, wherein the present application is acontinuation of U.S. patent application Ser. No. 12/353,961, filed Jan.14, 2009, pending, which published as no. US 2009/0121841 A1, which '961application is a continuation of U.S. patent application Ser. No.11/161,542, filed Aug. 8, 2005, now U.S. Pat. No. 7,522,568, whichpublished as no. US 2006/0023679 A1,

(a) which '542 application is a continuation-in-part of each of:

-   -   (1) application Ser. No. 10/604,032, filed Jun. 23, 2003, now        U.S. Pat. No. 6,934,540, which published as no. US 2004/0082296,        and which '032 application is a continuation-in-part of each of,        -   (A) application Ser. No. 09/681,282, filed Mar. 13, 2001,            now U.S. patent no. 6,745,027, which '282 application is a            nonprovisional of application Ser. No. 60/257,637, filed            Dec. 22, 2000, expired, and        -   (B) application no. PCT/US01/49513, filed Dec. 26, 2001,            expired, designating the United States and published in            English as WO 03/032501,            -   (i) which '513 international application is a                continuation-in-part of application Ser. No. 09/681,282,                filed Mar. 13, 2001, now U.S. Pat. No. 6,745,027, which                '282 application is a nonprovisional of application Ser.                No. 60/257,637, filed Dec. 22, 2000, expired,            -   (ii) and which '513 international application is a                nonprovisional of each of application Ser. Nos.                60/257,637, filed Dec. 22, 2000, and 60/257,398, filed                Dec. 22, 2000, both expired,    -   (2) application Ser. No. 10/514,336, filed Nov. 12, 2004, now        U.S. Pat. No. 7,209,771, which '336 application is a national        stage of application no. PCT/US03/14987, filed May 14, 2003,        expired, designating the United States and published in English        as WO 03/098851,        -   (A) which '987 international application is a            continuation-in-part of application Ser. No. 09/681,282,            filed Mar. 13, 2001, now U.S. Pat. No. 6,745,027, which '282            application is a nonprovisional of application Ser. No.            60/257,637, filed Dec. 22, 2000, expired,        -   (B) which '987 international application is a            continuation-in-part of application no. PCT/US01/49513,            filed Dec. 26, 2001, expired, designating the United States            and published in English as WO 03/032501,            -   (i) which '513 international application is a                continuation-in-part of application Ser. No. 09/681,282,                filed Mar. 13, 2001, now U.S. Pat. No. 6,745,027, which                '282 application is a nonprovisional of application Ser.                No. 60/257,637, filed Dec. 22, 2000, expired,            -   (ii) and which '513 international application is a                nonprovisional of each of application Ser. Nos.                60/257,637, filed Dec. 22, 2000, and 60/257,398, filed                Dec. 22, 2000, both expired,        -   (C) and which '987 international application is a            nonprovisional of each of application Ser. Nos. 60/380,195,            filed May 14, 2002, and 60/380,670, filed May 16, 2002, both            expired,

(b) and which '542 application is a nonprovisional of, and claims thebenefit under 35 U.S.C. §119(e) to, each of:

-   -   (1) application Ser. No. 60/595,233, filed Jun. 16, 2005,        expired,    -   (2) application Ser. No. 60/642,632, filed Jan. 10, 2005,        expired,    -   (3) application Ser. No. 60/687,073, filed Jun. 3, 2005,        expired,    -   (4) application Ser. No. 60/687,415, filed Jun. 3, 2005,        expired,    -   (5) application Ser. No. 60/688,737, filed Jun. 8, 2005,        expired,    -   (6) application Ser. No. 60/691,574, filed Jun. 17, 2005,        expired,    -   (7) application Ser. No. 60/691,718, filed Jun. 17, 2005,        expired,    -   (8) application Ser. No. 60/691,884, filed Jun. 17, 2005,        expired, and    -   (9) application Ser. No. 60/696,159, filed Jul. 1, 2005,        expired.

Each of the foregoing patent applications, patents, and patentapplication publications are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates broadly to wireless transceivers,including the design of a wireless transceiver as well as to forming adhoc networks with wireless transceivers and to communication protocolsbetween wireless transceivers.

BACKGROUND OF THE INVENTION

Wireless ad hoc networks allow node-to-node communication withoutcentral control or wired infrastructure. Such networks may have dynamic,randomly-changing, multihop topologies composed of wireless datacommunication links between the nodes.

Ad hoc networks are advantageous because they are inexpensive,fault-tolerant, and flexible. Various known methods relate to datatransmission within an ad hoc wireless data communication network.

However, most known methods do not address self-configuration ofwireless nodes for the formation and maintenance of efficient networktopology.

Known ad hoc networking methods typically organize the network on thebasis of geographic proximity of the nodes or the strength of signalsreceived by the various nodes. Known methods of ad hoc networkorganization also require nodes to regularly transmit networkinformation to all other nodes in the network, which results inincreased radio traffic and interference.

Increased radio interference inhibits the formation and maintenance ofad hoc networks having a large number of nodes and requires nodes totransmit at a greater power, which reduces their battery life.

Short range wireless technology utilizing standards based radiotechnology, such as the Bluetooth radio standard (hereinafter“Bluetooth”), promises to remove price barriers to mobile network use.

By doing so, wireless devices are becoming available for applicationswhere wired networks have been impracticable and in which prior wirelesscommunication networks have been too expensive or inflexible.

However, while Bluetooth radio technology is an ad hoc networkingsolution for personal data applications, it provides for only a limitednumber of communication channels, thereby restricting the number ofBluetooth devices that can communicate over an ad hoc network at anygiven time.

With regard to asset tracking, wireless data networks are known for usein warehouse management and other asset-tracking applications.

However, existing wireless data network technologies are not well suitedto asset tracking, which involves a large number of network nodes (e.g.,hundreds or even thousands).

Furthermore, existing wireless technologies are cost prohibitive, areprone to radio frequency (RF) interference, and consume a large amountof electrical power. Accordingly, wireless data networks are notcommonly used in asset tracking.

Another obstacle to widespread implementation of the use of standardsbased radios, such as Bluetooth radios, especially in asset-trackingapplications, is the limited life of the radio due to its powerconsumption.

Each standards based radio associated with an asset being tracked oftenoperates from a battery that is included within the housing of theradio.

The battery is able to effectively power the radio for only a shortperiod of time.

For example, a Bluetooth radio, whether of the class 1, 2, or 3 type,utilizes about 40 mAh of current when actively receiving transmissions.

Even in standby mode, wherein the radio is neither receiving nortransmitting but is in a low power consumption mode from which it canquickly return to an active state, such a radio utilizes about 10 mAh ofcurrent.

Bluetooth radios therefore can be expected to last less than aboutninety (90) days, and only half that long in fairly activeasset-tracking applications.

In view of the foregoing, it will be apparent that certain needs exist:for an improved low cost networking technology that has the benefits ofthe price and flexibility of standards based radios, but that overcomesthe limited networking capacity of this technology; for more efficientmethods of forming, organizing, and maintaining ad hoc wirelessnetworks; and for a wireless data network technology that accommodates alarge number of nodes, reduces RF interference, and consumes less power.A need also exists for a standards based radio device that consumes lesspower when awaiting the receipt of transmissions, thereby increasing theeffective useful life of the radio device. The present inventionaddresses one or more of these needs.

SUMMARY OF THE PRESENT INVENTION

Several aspects of the invention are briefly described.

In a first aspect, a method of forming a wireless data communicationnetwork among a plurality of transceivers, particularly for trackingassets associated with the transceivers and/or for acquiring data fromsensors associated with the transceivers, includes the steps of:assigning a common designation to a population of transceivers;selecting a primary transceiver from among the population oftransceivers, the remainder of the population of transceivers beingsecondary transceivers; and forming a common designation, hierarchicalad hoc network among the population of transceivers.

Another aspect of the present invention includes forming a wireless datacommunication network among a plurality of transceivers by: assigning afirst common designation to a first plurality of transceivers; assigninga second common designation to a second plurality of transceivers; andpropagating first and second common designation, hierarchical ad hoccommunication networks for transmitting data among the respective firstand second pluralities of transceivers based on their respective commondesignations, the first hierarchical ad hoc communication networkincluding a first root transceiver, and the second hierarchical ad hoccommunication network including a second root transceiver.

Still another aspect of the present invention includes the forming of ahierarchical ad hoc network, comprising the steps of: assigning a firstcommon designation or a second common designation to each of a pluralityof wireless transceivers, each of the wireless transceivers including adigital processor, a memory, and a common designation network formationroutine operable on the digital processor; and initiating the routinesof the wireless transceivers to automatically propagate, in the absenceof central control, a first hierarchical ad hoc network among thewireless transceivers of the first common designation and a secondhierarchical ad hoc network among the wireless transceivers of thesecond common designation, the first hierarchical network automaticallybeing organized so that it is logically distinct from the secondhierarchical network.

Yet another aspect of the present invention relates to a dynamicdistributed hierarchical database system. The dynamic distributedhierarchical database system includes a plurality of computer units eachhaving a respective common designation. Each computer unit includes: amemory unit for storing a profile representative of its commondesignation; an ad hoc common designation network formation routine incommunication with the memory for establishing a hierarchical ad hocnetwork with other computer units based on a shared common designationof the computer units; and a query handling routine for interpreting andresponding to database queries received from an application server whichdatabase queries are directed to computer units sharing the particularcommon designation.

An additional aspect of the present invention pertains to a method offorming a wireless data communication network among transceivers,wherein each transceiver includes a designation with a first pluralityof transceivers having a first common designation and a second pluralityof transceivers having a second common designation different from thefirst common designation. The method includes the steps of: forming anad hoc hierarchical class based network for each of the first pluralityand second plurality of transceivers; and communicating to an externalnetwork from each transceiver of each ad hoc hierarchical class basednetwork. Communication to the external network from each transceiver ofeach ad hoc hierarchical class based network is accomplished byestablishing a communication link between each transceiver in a level ofthe ad hoc hierarchical common designation network, other than thehighest level, with a transceiver in the next higher level of the ad hochierarchical common designation network such that transceivers passcommunications upward in the ad hoc hierarchical common designationnetwork; and establishing a communication link between a transceiver inthe highest level of the ad hoc hierarchical common designation networkand an external network access transceiver, such that communicationsfrom transceivers in the ad hoc hierarchical common designation networkare passed through the transceiver in the highest level of the ad hochierarchical common designation network to the external network accesstransceiver.

Another aspect of the present invention relates to a method forcommunicating to a recipient transceiver from a plurality oftransceivers, wherein the plurality of transceivers are located withinthe broadcast range of the recipient transceiver. The method comprisingthe steps of: transmitting a communication at a first power level suchthat only a first group of transceivers receive the broadcast, with thecommunication including a command causing each of the first group oftransceivers not to respond to a subsequent broadcast; and subsequentthereto, transmitting a communication at a second power level greaterthan the first power level such that a second group of transceiversgreater than and including the first group of transceivers receive thebroadcast, but such that only a limited number of transceivers of thesecond group respond to the broadcast. The limited number oftransceivers excludes the first group of transceivers.

In a feature of this aspect of the present invention, the plurality oftransceivers actually exceeds the number of transceivers from whichcommunications simultaneously can be received by the transceiver withoutradio frequency interference due to its channel capacity. In this case,the first group of transceivers comprises a number not greater than thenumber of transceivers from which communications can be received by thetransceiver without radio frequency interference due to its channelcapacity. The limited number of transceivers excludes the first group oftransceivers and also otherwise comprises a number not greater than thenumber of transceivers from which communications can be received by thetransceiver without radio frequency interference due to its channelcapacity.

Still yet another aspect of the present invention pertains to a wirelesstransceiver that includes a low power radio frequency (LPRF)communications device capable of powering down to conserve energy andcapable of powering up in response to an electronic signal. The wirelesstransceiver further includes, in accordance with the present invention,a second receiver that is physically connected to the input of the LPRFcommunications device and that provides the electronic signal forpowering up the LPRF communications component in response to receipt bythe second receiver of a radio frequency broadcast.

The wireless transceiver may be used to read wireless tags disposedexternally to and in proximity of the wireless transceiver, in whichcase the wireless transceiver is referred to herein as a wireless readertag (WRT). Consequently, in an aspect of the present invention, a WRTincludes a low power radio frequency (LPRF) communications componentcapable of powering down to conserve energy and capable of powering upin response to an electronic signal. The LPRF communications componentincludes a receiver and a transmitter for two-way radio communications.The WRT also includes a second receiver physically connected to theinput of the LPRF communications component. In response to receipt bythe second receiver of a radio frequency broadcast, the second receiverprovides the electronic signal in order to power up the LPRFcommunications component. Preferably, the LPRF communications componentand second receiver are hardwired within a housing of the WRT. The WRTalso may include, hardwired within the housing, a reader component forreading WTs disposed externally to and in proximity of the WRT. In suchcase, the reader component preferably is physically connected to theLPRF communications component for data exchange therebetween.

In another aspect of the present invention, a WRT, which can be used toread one or more WTs that are disposed externally to and in proximity ofthe WRT in response to a radio frequency broadcast, draws only on theorder of approximately 10 to 15 microamps of electric current whenawaiting for and receiving the radio frequency broadcast. Preferably, aLPRF communications component (which includes a receiver and atransmitter for two-way radio communications) and a second receiver arehardwired within a housing of the WRT. When included, a reader componentalso is hardwired within the WRT housing in physical connection with theLPRF communications component for data exchange therebetween.

In yet another aspect of the present invention, a method ofmanufacturing a WRT, which can be used to read one or more WTs disposedexternally to and in proximity of the WRT, includes the step ofhardwiring within a housing of the WRT: a low power radio frequency(LPRF) communications component capable of powering down to conservebattery power and capable of powering up in response to an electronicsignal, wherein the LPRF communications component includes a receiverand a transmitter for two-way radio communications; and a secondreceiver physically connected to the input of the LPRF communicationscomponent, with the second receiver generating the electronic signal inorder to power up the LPRF communications component in response toreceipt by the second receiver of a radio frequency broadcast. Themethod also may include the step of hardwiring into the WRT housing areader component for reading the WTs, with the reader componentphysically connected to the LPRF communications component for dataexchange therebetween;

In certain preferred embodiments of the present invention, the WRTpreferably draws on the order of only about 10 to 15 microamps ofcurrent when awaiting for and receiving the radio frequency broadcast.The LPRF communications component in particular draws on the order ofabout 40 mA of current when powered up; draws on the order of about 10mA of current when powered down to a “standby” mode; and drawsapproximately no current when powered down to an “off” state. The LPRFcommunications component preferably comprises a Bluetooth radio or otherstandards based radio. The second receiver draws on the order of 15microamps of electric charge when awaiting for and receiving the radiofrequency broadcast.

In additional features of certain preferred embodiments, the secondreceiver provides the electronic signal by toggling a line connectingthe second receiver with the LPRF communications component, and the LPRFcommunications device is programmed to power down when no longeractively transmitting or receiving. The second receiver provides powerto the voltage regulators supplying power to the LPRF communicationsdevice causing it to power up or “boot up.” The second receiver may bepassive, i.e., have no energy source; however, the second receiverpreferably includes a battery to increase its sensitivity and, thus,significantly increase the range within which it may detect atransmission over the range that it otherwise would have without use ofan energy source.

A modified wireless tag may comprise the second receiver. Such amodified wireless tag preferably includes: a radio frequency detectorcomponent, a memory component, and an application specific integratedcircuit (ASIC) component. Either the memory component or the ASICcomponent may stores an identification therein.

In this regard, the radio frequency broadcast, to which the secondreceiver responds by providing the electronic signal at the input of theLPRF communications device, preferably includes therein theidentification that is stored within the WRT when the broadcast isintended to activate the WRT. Furthermore, the second receiverpreferably responds to a radio frequency broadcast by providing theelectronic signal at the input of the LPRF communications device only ifthe radio frequency broadcast includes the identification.

The identification itself may be permanently stored within the secondreceiver. The identification also may uniquely identify the WRT or,alternatively, the identification may represent a WRT class or a WTclass. The identification may also represent a selected plurality ofWRTs.

The second receiver preferably includes an antenna, which may be thesame as or different from the antenna utilized by the LPRFcommunications component or different. The second receiver alsopreferably has an energy source, which may be the same as or differentfrom the energy source utilized by the LPRF communications component.

The WRTs of certain embodiments of the present invention are preferablyutilized in asset-tracking applications. The radio frequency utilized bythe WRTs preferably is about 2.4 GHz. In this context, the WTs that areread by the reader components of the WRTs preferably are associated withthe assets to be tracked, with each of these WTs comprising aradio-frequency transponder. Alternatively, WRTs themselves may beassociated with assets to be tracked, thereby serving the function ofWTs.

In accordance with one or more aspects of the present invention, the WRTmay include a sensor component physically connected to the LPRFcommunications component for data exchange therebetween. The sensorcomponent may include a motion detector; a digital camera; a microphone;a thermometer; and/or a global positioning system (GPS) receiver.

In accordance with one or more aspects of the present invention, the WRTfurther may include an external network communications componentphysically connected to the LPRF communications component for dataexchange therebetween. In this regard, the external networkcommunications component may comprise a satellite transceiver and/or acellular transceiver.

In yet another aspect, an asset-tracking system utilizes one or more ofthe foregoing WRTs in accordance with the present invention, including amethod of forming an ad hoc hierarchical data communication networkutilizing one or more WRTs. Such an asset-tracking system alsopreferably utilizes class-based, ad hoc hierarchical networks.

In a method of forming a wireless data communication network among WRTsin accordance with the foregoing, each WRT includes a designation with afirst plurality of WRTs having a first common designation and a secondplurality of WRTs having a second common designation different from thefirst common designation. The method includes the steps of: forming anad hoc hierarchical network for each of the first plurality and secondplurality of WRTs; and communicating to an external network from eachWRT of each ad hoc hierarchical network by, (i) establishing acommunication link between each WRT in a level of the ad hochierarchical network, other than the highest level, with a WRT in thenext higher level of the ad hoc hierarchical network such that WRTs passcommunications upward in the ad hoc hierarchical network; and (ii)establishing a communication link between a WRT in the highest level ofthe ad hoc hierarchical network and an external network accesstransceiver, such that communications from WRTs in the ad hochierarchical network are passed through the WRT in the highest level ofthe ad hoc hierarchical network to the external network accesstransceiver.

In another method of forming a wireless data communication network amongWRTs in accordance with the foregoing, each WRT includes a classdesignation with a first plurality of WRTs having a first classdesignation and a second plurality of WRTs having a second classdesignation different from the first class designation. The methodincludes the steps of: forming an ad hoc hierarchical class-basednetwork for each of the first plurality and second plurality of WRTs;and communicating to an external network from each WRT of each ad hochierarchical class-based network by, (i) establishing a communicationlink between each WRT in a level of the ad hoc hierarchical class-basednetwork, other than the highest level, with a WRT in the next higherlevel of the ad hoc hierarchical class-based network such that WRTs passcommunications upward in the ad hoc hierarchical class-based network;and (ii) establishing a communication link between a WRT in the highestlevel of the ad hoc hierarchical class-based network and an externalnetwork access transceiver, such that communications from WRTs in the adhoc hierarchical class-based network are passed through the WRT in thehighest level of the ad hoc hierarchical class-based network to theexternal network access transceiver. The step of forming an ad hochierarchical class-based network for each of the first plurality andsecond plurality of WRTs preferably includes the steps of: filtering, byeach WRT, transmissions from other WRTs for an identification of itsclass designation within the transmission; transmitting, from a primaryWRT of the first plurality, a primary availability signal including anidentification of the first class designation and an identification ofthe primary WRT transmitting the primary availability signal;transmitting, from a primary WRT of the second plurality, a primaryavailability signal including an identification of the second classdesignation and an identification of the primary WRT of the secondplurality transmitting the primary availability signal; transmitting,from a WRT receiving a primary availability signal having anidentification therein of its class designation, a registration signalincluding an identification of the class designation and anidentification of the WRT transmitting the registration signal; andidentifying a WRT transmitting a registration signal as a secondary WRTby a primary WRT of the same class designation, the primary WRT therebyassuming a higher level in the ad hoc hierarchical class-based networkrelative to the said identified secondary WRT such that communicationfrom the secondary WRT to the external network is passed to the primaryWRT.

A method for communicating to a WRT in accordance with the foregoingfrom WTs located within the broadcast range of the WRT includes thesteps of: transmitting by the WRT a communication at a first power levelsuch that only a first group of the WTs receive the broadcast, thecommunication including a command causing each of the first group of WTsnot to respond to a subsequent broadcast; and subsequent theretotransmitting by the WRT a communication at a second power level greaterthan the first power level such that a second group of WTs greater thanand including the first group of WTs receive the broadcast, but suchthat only a limited number of WTs of the second group respond to thebroadcast, the limited number of WTs excluding the first group of WTs.

A second method for communicating to a WRT in accordance with theforegoing from WTs located within the broadcast range of the WRT appliesto the situation wherein the WTs exceed the number of WTs from whichcommunications ordinarily can be received by the WRT without radiofrequency interference due to its channel capacity. In this regard, themethod includes the steps of: transmitting by the WRT a communication ata first power level such that only a first group of the WTs receive thebroadcast, the first group in number of WTs being not greater than thenumber of WTs from which communications can be received by the WRTwithout radio frequency interference due to its channel capacity, thecommunication including a command causing each of the first group of WTsnot to respond to a subsequent broadcast; and subsequent theretotransmitting by the WRT a communication at a second power level greaterthan the first power level such that a second group of WTs greater thanand including the first group of WTs receive the broadcast, but suchthat only a limited number of WTs of the second group respond to thebroadcast, the limited number of WTs excluding the first group of WTsand comprising not greater than the number of WTs from whichcommunications can be received by the WRT without radio frequencyinterference due to its channel capacity.

In addition to the aforementioned aspects and features, the presentinvention further encompasses the various possible combinations of suchaspects and features, including those of the incorporated referencesfrom which priority is claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

Further aspects, feature, benefits, and advantages of the presentinvention will be apparent from a detailed description of preferredembodiments of the present invention taken in conjunction with thefollowing drawings, wherein similar elements are referred to withsimilar reference numbers, and wherein:

FIG. 1 illustrates various network components and an example arrangementin the context of a warehouse application in accordance with the presentinvention.

FIG. 2 is a flowchart illustrating a preferred operation of the CBNFroutine operating on Wireless Reader Tags in accordance with the presentinvention.

FIGS. 3-11 illustrate a time sequence that depicts Wireless Reader Tagsof arbitrary classes “circle” and “triangle,” transmitting a series ofmessages in the course of self-organizing a hierarchical network using abottom-up propagation approach.

FIGS. 6A, 8A, 9A, 10A, and 11A illustrate the topology of the ad hocnetwork formed at the stages depicted in corresponding FIGS. 6, 8, 9,10, and 11, respectively.

FIGS. 12-21A illustrate a time sequence of ad hoc network formationusing a top-down propagation approach.

FIG. 22 illustrates a step-power filtering routine utilized by aWireless Reader Tag in accordance with the present invention.

FIG. 23 illustrates in block diagram a Gateway making a WRT Broadcast toa plurality of WRTs in accordance with a preferred embodiment of thepresent invention.

FIG. 24 illustrates in block diagram a preferred architecture of a WRTof FIG. 23.

FIG. 25 illustrates in block diagram a preferred architecture of the WTcomponent of the WRT of FIG. 24.

FIG. 26 comprises Table 1 referenced below.

FIG. 27 comprises Table 2 referenced below.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

As a preliminary matter, it will readily be understood by those personsskilled in the art that the present invention is susceptible of broadutility and application in view of the following detailed description ofthe preferred devices and methods of the present invention. Manydevices, methods, embodiments, and adaptations of the present inventionother than those herein described, as well as many variations,modifications, and equivalent arrangements, will be apparent from orreasonably suggested by the present invention and the following detaileddescription thereof, without departing from the substance or scope ofthe present invention. Accordingly, while the present invention isdescribed herein in detail in relation to preferred devices, methods andsystems, it is to be understood that this disclosure is illustrative andexemplary and is made merely for purposes of providing a full andenabling disclosure of the preferred embodiments of the invention. Thedisclosure herein is not intended nor is to be construed to limit thepresent invention or otherwise to exclude any such other embodiments,adaptations, variations, modifications and equivalent arrangements, thepresent invention being limited only by the claims appended hereto andthe equivalents thereof.

Preferred embodiments of the present invention relate to asset trackingand/or monitoring. Other preferred embodiments relate to providing aremote sensor interface (RSI) network for the receipt and communicationof sensor-acquired data. The RSI network may be utilized in conjunctionwith asset tracking and/or monitoring, in which case the sensor-acquireddata may relate to information obtained from sensors associated with theassets being tracked and/or monitored. The following detaileddescription relates primarily to asset tracking and/or monitoring, butequally disclose the RSI networks of the present invention whether usedin asset tracking and/or monitoring, or otherwise.

Accordingly, with regard to asset tracking and monitoring, each asset tobe tracked preferably is tagged with a wireless transceiver (hereinafterreferred to as a “Wireless Tag” or “WT”) and reading the Wireless Tagusing another wireless transceiver (hereinafter referred to as a“Wireless Reader Tag” or “WRT”).

The Wireless Tag itself preferably is semi-passive, although a passive,active, or other type of Wireless Tag could be used within the scope ofthe present invention. The Wireless Reader Tag itself preferable isactive. A passive transceiver, such as an RFID tag, receives andtransmits primarily using inductive energy. A semi-passive transceiverreceives primarily using inductive energy and transmits using internallystored energy, such as a battery. An active transceiver receives andtransmits using internally stored energy, such as a battery.

In the preferred embodiments, the Wireless Tags are radio-frequencytransponders (“RFTs”), and the Wireless Reader Tags are wirelesstransceivers generally comprising low-power radio frequency (“LPRF”)devices capable of transmitting and receiving data packets. As usedherein, a LPRF device refers generally to a two-way wirelessradio-frequency data communication device that transmits data inpackets, and is not limited to a particular signal strength or powerconsumption.

Each Wireless Tag includes a unique identification (hereinafter “WT ID”)stored therein that uniquely identifies the Wireless Tag intransmissions made by the Wireless Tag and, likewise, each WirelessReader Tag includes a unique identification (hereinafter “WRT ID”)stored therein that uniquely identifies the Wireless Reader Tag intransmissions made by the Wireless Reader Tag.

The Wireless Reader Tags preferably operate in accordance with standardsbased radios and especially with Bluetooth standards—an industry widewireless radio specification. However, it should be understood that theinvention is not limited to use with Bluetooth technology, but can beused with any wireless transceiver having the capability to communicatedirectly with other wireless transceivers, such as wireless Ethernettransceivers, 802.11, Home RF, and others.

In accordance with the present invention, each Wireless Tag alsoincludes, apart from its WT ID, a “class designation” representative ofan attribute, characteristic, relation, or behavior of the asset (andnot the Wireless Tag itself), and each Wireless Tag is said to belongto, or be a member of, a particular WT Class based on its classdesignation. Identification of the WT Class for which a particularWireless Tag is designated preferably is stored on the Wireless Tag andis utilized by the Wireless Tag in screening broadcasts for determiningwhether to respond thereto with a transmission.

The WT Class may represent any type of identification, as desired. Forinstance, a particular WT Class could represent a category of an asset,such as a ball (identified by /ball); a subcategory such as a soccerball (identified by /soccer ball); or a subcategory of the subcategory(a sub-subcategory), such as a size 5 soccer ball (identified by/size_(—)5_soccer_ball). When the WT Class represents a subcategory orsub-category, for example, the WT Class may also represent the categoryor subcategory, respectively, abstracted from the subcategory orsub-category. Thus, a WT Class representing a sub-subcategory equal to/ball/soccer_ball/size_(—)5_soccer_ball also inherently identifies asubcategory (soccer_ball) and a category (ball). Alternatively, the a WTClass may be intentionally limited to identification only of thesub-subcategory (/size_(—)5_soccer_ball). If so limited, additionalinformation inferred from this identification about the subcategoryand/or category of such WT Class then may be maintained in memory on theWireless Reader Tag (described below) or remotely in categorydictionaries or category rule sets.

When a broadcast or multicast is made to the Wireless Tags (hereinafter“WT Broadcast”), each Wireless Tag is capable of identifying a specifiedWT Class in the WT Broadcast and replying to the WT Broadcast with itsown transmission when the specified WT Class matches its WT Class. Ifthe WT Class does not match its class designation, then the Wireless Tagdoes not respond to the WT Broadcast and it makes no transmission. Inthis regard, each Wireless Tag is a transponder that may be selectivelyactivated. Semi-passive transceivers that are capable of being used torespond to targeted broadcasts in accordance with the present invention,and not to every broadcast received, are well known within the art and,accordingly, the specific design of such semi-passive transceivers formsno part of the present invention.

Each Wireless Reader Tag also includes a class designation, and eachWireless Reader Tag is said to belong to, or be a member of, a WRTClass. Preferably each Wireless Reader Tag is associated with at leastone WT Class for reading Wireless Tags that are members thereof. In thisregard, the Wireless Reader Tag communicates with (or “reads”) thoseWireless Tags having a WT Class with which it is associated by making aWT Broadcast specifying the WT Class in the transmission. Theidentification of associated WT Classes of a Wireless Reader Tagpreferably is preprogrammed into the memory of, or otherwise maintainedin, the Wireless Reader Tag. Active transceivers that are capable ofbeing used to make broadcasts that identify targeted semi-passivetransceivers for response are well known within the art and,accordingly, the specific design of such active transceivers forms nopart of the present invention. Preferably, however, each Wireless ReaderTag includes a digital processor and memory for storing the WRT Classthereof and associated WT Classes, the members of which are to be readby the Wireless Reader Tag.

Preferred embodiments of each WRT in accordance with certain aspects ofthe present invention are disclosed in further detail below under theheading “Preferred WRT Architecture.”

In one aspect of the invention, a class adoption step also is utilizedin which a WRT Class is adopted by a Wireless Reader Tag that isdetected as being the WRT Class of a nearby Wireless Reader Tag, or thatis associated with a detected WT Class of a nearby Wireless Tag.Typically, such class adoption is performed only when the adoptingWireless Reader Tag is unable to participate in the ad hoc hierarchicalnetwork formation because of a missing or corrupted class designation.Moreover, in some circumstances such a class adoption step may be usefuleven if the adopting Wireless Reader Tag has sufficient classdesignation information to support communication. For example, aWireless Reader Tag attached to a pallet could periodically update itsclass designation by detecting the WRT Classes of nearby Wireless ReaderTags and the corresponding WT Classes of nearby Wireless Tags (e.g.,those attached to items placed on a pallet). Alternatively a WirelessReader Tag can be manually programmed with a class designation by use ofa handheld communicator (hereinafter “Communicator”). The Communicatoris a sort of remote control device that allows a human operator toprogram Wireless Reader Tags and to query Wireless Tags. Preferably, theCommunicator includes a LPRF device that is controlled by applicationsoftware designed to facilitate manual human interaction andcommunication with nearby Wireless Reader Tags and Wireless Tags. Inpreferred embodiments, the Communicator comprises a PDA, such as thoseavailable from Palm Corp., that is appropriately configured for use withthe present invention.

In reading Wireless Tags, a Wireless Reader Tag is capable ofcommunicating with a limited number of Wireless Tags at any given time.Accordingly, if a large number of Wireless Tags are to be read by aparticular Wireless Reader Tag, the Wireless Tags are read using astep-power filtering routine in accordance with the present invention.In this regard, a Wireless Reader Tag is capable of transmitting atdifferent power levels. By transmitting a different consecutive powerlevels, a Wireless Reader Tag may read a large number of Wireless Tagsthat otherwise would not be read due to RF interference.

With reference to FIG. 22, a Wireless Reader Tag “M” is shown spaced atdifferent distances to Wireless Tags S₁,S₂,S₃,S₄. In accordance with thestep-power filtering routine, the Wireless Reader Tag broadcasts at afirst power level 10 a transmission specifying the WT Class of all ofthe illustrated Wireless Tags S. The broadcast is received by theclosest three Wireless Tags shown within the inner circle 1010, whichrepresents the effective transmission range of the Wireless Reader Tagat the first power level. The broadcast includes, inter alia, a commandto ignore subsequent transmission specifying the same WT Class within apredetermined time period thereafter. The Wireless Tags receiving thistransmission then respond appropriately and power down for thepredetermined time period.

Next, the Wireless Reader Tag broadcasts at a second, stronger powerlevel 20 a transmission specifying the same WT Class. The broadcast isreceived by the closest six Wireless Tags shown within the inner circle2020, which represents the effective transmission range of the WirelessReader Tag at the second power level. The broadcast includes, interalia, a command to ignore subsequent transmission specifying the same WTClass within a predetermined time period thereafter. The three outermostWireless Tags S₂ receive this transmission, respond appropriately, andthen power down for the predetermined time period. The innermostWireless Tags S₁ do not respond, as each has previously been instructedto ignore this subsequent transmission.

This process then repeat two more times, whereby all fifteen WirelessTags have been read. Specifically, the Wireless Reader Tag nextbroadcasts at a third, stronger power level 30 a transmission specifyingthe same WT Class. The broadcast is received by the closest elevenWireless Tags shown within the inner circle 3030, which represents theeffective transmission range of the Wireless Reader Tag at the thirdpower level. The broadcast includes, inter alia, a command to ignoresubsequent transmission specifying the same WT Class within apredetermined time period thereafter. The five outermost Wireless TagsS₃ receive this transmission, respond appropriately, and then power downfor the predetermined time period. The innermost Wireless Tags S₁,S₂ donot respond, as each has previously been instructed to ignore thissubsequent transmission.

Finally, the Wireless Reader Tag next broadcasts at a fourth, yetstronger power level 40 a transmission specifying the same WT Class. Thebroadcast is received by all Wireless Tags shown within the inner circle4040, which represents the effective transmission range of the WirelessReader Tag at the fourth power level. The broadcast includes, interalia, a command to ignore subsequent transmission specifying the same WTClass within a predetermined time period thereafter. The four outermostWireless Tags S₄ receive this transmission, respond appropriately, andthen power down for the predetermined time period. The innermostWireless Tags S₁,S₂,S₃ do not respond, as each has previously beeninstructed to ignore this subsequent transmission. In an alternativestep-power filtering technique, the power level of the broadcast isincluded in the transmission. Then, as each Wireless Tag receives thebroadcast, the power level is noted and a range thereof is used with theWT Class for prescreening of further transmissions. In this regard, onlythose transmissions falling within the predetermined range about thepower level of the broadcast are received and processed by theparticular Wireless Tags. Thereafter, a “reset” command is broadcast toall of the Wireless Tags in order to enable receipt thereafter of abroadcast at any power level, or alternatively, the power levelscreening is dropped after a predetermined time period.

The WRT class designations primarily are used by Wireless Reader Tag toscreen each broadcast or multicast intended for receipt by a particularclass of Wireless Reader Tags (hereinafter “WRT Broadcast”). Typically,a command, query, or the like (generically referred to as a message) iscommunicated in a transmission to members of a WRT Class in a WRTBroadcast as part of a data packet that begins with a preamble includingan identification of the WRT Class intended as the target of thebroadcast. Other information may also be included in the data packet forscreening purposes by each Wireless Reader Tag. Wireless Reader Tagswithin range of the WRT Broadcast awake from a standby mode to receivethe data packet, but only process the message therein with possibletransmissions in response thereto when the WRT Class of the preamblematches the WRT Class of the Wireless Reader Tag (and when the otherscreening information, if present, also is matched). If there is nomatch, then the particular Wireless Reader Tag does not process themessage, drops the data packet, and returns to standby mode.

A Wireless Reader Tag or a Wireless Tag also may store in memoryadditional information such as: sensor derived information (e.g.,temperature, humidity, altitude, pressure); a priority designation toprovide improved response to selected broadcasts; a privilege level(e.g., “visitor,” “employee,” “manager,” “administrator,” and “superuser”); time-sensitive information (e.g., synchronization timing,real-time sensor data, and GPS data); a characteristic of the particulartagged asset (e.g., serial number, status, process step, physicallocation, color, size, density); and/or a behavior of the tagged asset(e.g., temperature sensitivity, light sensitivity, shelf life). AWireless Reader Tag also may store a WRT rank in a hierarchical ad hocnetwork formed by the Wireless Reader Tags (e.g., “primary” or “master,”“secondary” or “slave,” “sub-primary,” “tertiary”); and/or anidentification of the WT Class for which a particular Wireless Tag isdesignated, indexed by WT ID for the particular Wireless Tag, especiallyif the Wireless Tag can store only the WT ID (e.g., when the WirelessTag is passive).

Preferred WRT Architecture

Whether utilized in asset-tracking applications, sensor derivedinformation gathering, or otherwise, the preferred WRT architecturesignificantly prolongs the useful life of a WRT.

In this regard, FIG. 23 illustrates in block diagram a Gateway 5000making a WRT broadcast 5002 to a plurality of WRTs 5008 in accordancewith the present invention. As discussed in greater detail below withreference to network formation, the Gateway 5000 represents the juncturebetween the networks formed by the WRTs 5008 and an external network,such as the Internet. Specifically, the Gateway 5000 is the NetworkInterface Module (“NIM”) in FIG. 23 providing the wireless interfaceinto the radio network of and controlling the messaging to the WRTs5008. In this regard, the Gateway 5000 preferably includes softwareallowing it make broadcasts to and communicate with the WRTs 5008. Insuch communications, the Gateway 5000 preferably sends out a lowfrequency message in the band of the LPRF communications component 5010of the WRTs 5008 (described in detail below). The message m(t)preferably is modulated on a carrier frequency, and the m(t) is likelyto have a bias (k) due to the other radio communications in the sameband. The m(t) will significantly reduce false turn on and provide themechanism to wake the radios based on an object identifier, name, orclassification (as described in detail below, once the WT component inthe WRT receives the proper message from the Gateway, the WT component“wakes up” the LPRF communications component in the WRT).

In forwarding communications between the external network and the radionetwork of the WRTs 5008, the Gateway 5000 translates a radio linkprotocol to Ethernet, PSTN (Public Switched Telephone Network), MobilePhones (including GSM, TDMA, CDMA, PDC, AMPS, Ricochet, etc.) and otherdata communications networks that allows the information to betransferred to a database on the Internet or an Intranet. The Gateway5000 thus serves an external network communications function, providingthe WRTs 5008 with an avenue for communication to external devicesconnected to the Internet.

Referring again to FIG. 23, the Gateway 5000 itself preferably includesa network card component 5004 for interfacing with the external networkusing the appropriate protocols and a WRT component 5006 forcommunicating with the WRTs 5008 using the appropriate protocols. TheWRT component 5006 interfaces to the network card 5004, and the WRTcomponent 5006 preferably comprises a LPRF communications component,such as a class 1 Bluetooth radio, for communicating directly with theLPRF communications component of each WRT 5008, as described in greaterdetail below. Furthermore, the WRT component 5006 may further include areceiver circuit for performing the “tag turn-on” function of thepresent invention, in which case the Gateway 5000 may power off when notin use and be awaken by an appropriate broadcast when communication byway of the Gateway 5000 is desired. This is especially advantageous whenthe Gateway 5000 itself is powered by an internal energy source, such asa battery.

Each WRT 5008 shown in FIG. 23 preferably is an active transceiver andincludes several components. Specifically, with reference to FIG. 24,each of the WRTs 5008 includes a LPRF communications component 5010, areader component 5012 physically connected to the LPRF communicationscomponent 5010 for data exchange therebetween, and a WT component 5014physically connected to an “activation” input of the LPRF communicationscomponent 5010 for performing the “tag turn-on” function of the presentinvention. These components are hardwired into the WRT housing 5016 ofthe WRT 5008. In this hardwiring, the WT component 5014 is physicallyconnected to the activation input of the LPRF communications component5010 by line 5018, and the reader component 5012 is physically connectedto the LPRF communications component 5010 by line 5020. Each WRT 5008also includes an energy source, such as a battery (not shown), as wellas an antenna (not shown).

The reader component 5012 preferably is connected to the LPRFcommunications component 5010 through a serial port of the LPRFcommunications component 5010. Furthermore, the reader component 5012preferably comprises an RFID tag reader for reading WTs that compriseRFID tags. However, in alternative preferred embodiments, if the WTs tobe read comprise standards based radios, such as class 1 or class 2Bluetooth radios, then the LPRF communications component 5010 itself iscapable of communicating directly with the WTs, and the reader component5012 need not even be included in the WRT 5008.

The WT component 5014 itself, like the WRT 5008, includes severalcomponents. As shown in FIG. 25, these components include a radiofrequency (RF) detector component 5022, an application-specificintegrated circuit (ASIC) component 5024, and a memory component 5026.The WT component 5014 also includes an energy source, such as a battery5026, as well as an antenna 5028. The antenna 5028 of the WT component5014 anchor the battery 5026 of the WT component 5028 may be shared withthe LPRF communications component 5008. Alternatively, the antenna 5028and/or the battery 5026 may be independent from that of the LPRFcommunications component 5008.

In variations of preferred embodiments, and in further accordance withthe present invention, a WRT may include an external networkcommunications component physically connected to the LPRF communicationscomponent for data exchange therebetween. In this regard, the NIM maycomprise a satellite transceiver and/or a cellular transceiver, and theLPRF communications component preferably includes a port for interfacingwith the satellite transceiver anchor cellular transceiver. If the WRTincludes an external communications component, then the WRT may directlycommunicate with an external network without relaying communicationsthrough the Gateway.

The WRT additionally, or alternatively, may include a sensor componentphysically connected to the LPRF communications component by way of anappropriate port for data exchange therebetween. The sensor componentmay include a motion detector; a digital camera; a microphone; atemperature gauge; a thermistor; a vibration sensor; anchor a globalpositioning system (GPS) receiver. By including the sensor component aspart of the WRT, data obtained from the sensor component can becommunicated from the WRT by selectively activating the WRT and sendinga query command to the WRT regarding the desired sensor information. TheWRT also may be programmed to transmit an alert or other communicationbased upon the occurrence of predetermined sensor derived information.

In operation, the LPRF communications component 5010 communicates withthe reader component 5012 in reading WTs located within the vicinity ofthe WRT 5008, and the LPRF communications component 5010 receives andtransmits data to other WRTs 5008 or to a Gateway 5000 (specifically,the WRT component 5006 of the Gateway 5000). Furthermore, the LPRFcommunications component 5010 preferably is programmed to power down toan “off” state in order to conserve battery power when the LPRFcommunications component 5010 no longer is actively transmitting orreceiving data packets. The LPRF communications component 5010 also maybe capable of powering power down to a standby mode, in which case theLPRF communications component 5010 preferably includes a timer circuitor other microprocessor that automatically controls powering up after apredetermined period of time has elapsed since powering down to thestandby mode.

The WT component 5014 physically connected to the activation input ofthe LPRF communications component 5010 provides the electronic signalfor waking up, i.e., activating, the LPRF communications component 5010.In this regard, the WT component 5014 generates this electronic signalby toggling the line 5018 that runs from the WT component 5014 to theLPRF communications component 5010 in response to receipt by the WTcomponent 5014 of a radio frequency broadcast.

Furthermore, in accordance with the present invention, the radiofrequency broadcast to which the WT component 5014 responds is a“targeted” broadcast. In this respect, the broadcast preferably includesin a preamble thereof one or more target identifications. The targetedbroadcast that awakens a particular WRT may originate from a Gateway,such as Gateway 5000 of FIG. 23. The targeted broadcast may alsooriginate from or be rebroadcast by the LPRF communications component ofanother WRT 5008.

The WT component 5014 preferably stores (in read only or read/writememory) an identification in its memory component 5026 and/orpermanently stores an identification in the integrated circuits of itsASIC component 5024, and when a broadcast is received, the WT component5014 screens or filters the broadcast to determine if the targetidentification in the broadcast matches the identification stored in theWT component 5014. If there is no match, the WT component 5014 does notawaken the LPRF communications component 5010 and continues to await abroadcast containing a matching identification.

On the other hand, a match results in the WT component 5014 generatingthe electrical signal by toggling the line 5018, which awakens the LPRFcommunications component 5010. The WT component 5014 responds to a radiofrequency broadcast in this manner preferably only if the radiofrequency broadcast includes a target identification matching its storedidentification. The stored identification itself may uniquely identifyits WRT or, alternatively, the identification may represent a WRT classor a WT class. The identification also may represent a selectedplurality of WRTs such that specific WRTs respond out of the totalpossible WRTs that otherwise could respond.

It thus will be apparent that, in its simplest form, the WT componentneed only comprise at a minimum a “receiver” circuit, as the WTcomponent need only receive incident RF energy and be capable ofresponding by providing the electronic signal to wake up the LPRFcommunications component. Such a receiver circuit is common, and isfound, for example, in the simple and inexpensive Frequency-Shift-Key(FSK) radios, Phase-Modulated (PM) radios, and Amplitude-Modulated (AM)radios.

In commercial practice, for example, the WT component could comprise asimple RFID tag modified to provide the wake up signal to the LPRFcommunications component. Such a wireless tag in standard operation“chirps” in response to receipt of incident RF energy, and the RFID tagwould only need to be modified in order to channel the energy otherwiseused for the “chirp” to the input of the LPRF communications componentin order to wake it up. The present invention thus provides a method ofusing “wireless tag technology” (i.e., the receiver circuit of wirelesstags) to wake the LPRF communications component when communication needsto commence.

It further will be apparent that a characteristic of a wirelesstransceiver of the present invention, such as a preferred WRT, includestwo receivers and at least one transmitter. A receiver and transmitterpair is included in the LPRF communications component, and a secondreceiver is included in the WT component. Additionally, the range atwhich the second receiver is capable of detecting transmissions is atleast approximately commensurate with the range at which the transmitteris capable of sending transmissions.

The advantages of this arrangement originates from the power consumptionof the LPRF communications component (the transmitter/receiver pair)while awaiting receipt of transmissions versus that of the WT component(the second receiver). The LPRF communications component, whichpreferably comprises a Bluetooth radio, draws on the order ofapproximately 40 mA of current when awaiting receipt of a radiofrequency broadcast and draws on the order of approximately 10 mA ofcurrent when powered down to a standby mode. The LPRF communicationcomponent draws approximately no current when powered down to an offstate. In contrast, the WT component comprises at least a receivercircuit that only draws on the order of approximately 10 to 15 microampsof current while awaiting receipt of the radio frequency broadcast.Consequently, with the LPRF communications component powered off, theWRT overall draws only on the order of approximately 10-15 microamps ofcurrent attributable to the WT component while awaiting receipt of theradio frequency broadcast. Without the WT component, the LPRFcommunications component would not power down to the off state betweentime periods of actively receiving and transmitting but, instead, onlywould power down to standby mode and, thus, the WRT overall would drawon the order of approximately 10 mA of current. Consequently, byproviding the WT component as part of the WRT, the LPRF communicationscomponent may power down to the off state such that the currentrequirement of the WRT is reduced three orders of magnitude, i.e., frommilliamps to microamps.

This significant reduction in power consumption while awaiting receiptof a targeted radio frequency broadcast practically removes thelimitation on the WRT's useful life that otherwise arises from its powerconsumption, thus providing tremendous advantage in increasing theuseful life of the WRT. Indeed, whereas the energy source incorporatedinto a WRT is anticipated to last for about 90 days or less beforebecoming depleted of charge, it is anticipated that the same energysource incorporated into a WRT of the present invention, which includesthe WT component, would never be depleted of charge during standardoperations of the WRT. Rather, it is anticipated that the energy sourceitself first would fail before becoming depleted from standard WRToperations. The WRT of the present invention is expected to lastyears—not days—and is expected to exceed the useful life of the energysource itself, which now presents the new limiting factor in determininga WRT's useful life.

WRTs of the present invention preferably are utilized in sensorinformation collecting and/or asset-tracking applications, and methodsfor forming ad hoc networks by these WRTs will now be described indetail. In either context, the radio frequency utilized by the WRTspreferably is 2.4 GHz, for which no license is required in any country.Furthermore, in the asset-tracking context utilizing the WRTs preferablyread wireless tags that, themselves, are associated with the assets tobe tracked. In other alternative embodiments, however, the WRTs alsoserve the wireless tag function, with each WRT being associated with anasset to be tracked. In these embodiments, a reader component of the WRTmay be omitted if no wireless tag is to be read by the WRT.

Class-Based Network Formation

In further accordance with the present invention, each of the WirelessReader Tags also includes a class-based network formation (CBNF) routinethat enables the Wireless Reader Tags to coordinate with one another incollectively forming hierarchical ad hoc networks, each network beingdefined by Wireless Reader Tags of a common WRT Class (hereinafter“Class-Based Network”). The CBNF routine is executed upon startup of theWireless Reader Tag, on specific command broadcast to the WirelessReader Tag, or as otherwise needed (such as to maintain an ad hocnetwork). The CBNF routine is implemented in software operable on thedigital processor of each Wireless Reader Tag in the preferredembodiments. Alternatively, the CBNF routine is implemented in otherways, such as hardwired logic circuitry in each of the Wireless ReaderTags. As described in detail below, each Class-Based Network is ahierarchical network that provides an efficient topology for selectivecommunication among Wireless Reader Tags of the same WRT Class.

WRT Broadcasts are made by a network interface module (hereinafter“Gateway”) that serves as a communication link between the ad hochierarchical networks established by the Wireless Reader Tags and anexternal network, such as a local area network (LAN), wide area network(WAN), or the Internet. The Gateway includes at least a networkinterface and an RF interface for communication with Wireless ReaderTags of the ad hoc networks. An asset-tracking application server orequivalent computer system is connected with the external network andobtains through the ad hoc networks information on the tagged assets forcompilation, analysis, and/or display.

Communication between the Gateway and a Wireless Reader Tag of thehighest hierarchical level in each Class-Based Network may beestablished utilizing step-power filtering technique if a number ofClass-Based Networks otherwise exceeds the multiple channelcommunication capabilities of the Gateway. In this respect, the Gatewayis enabled to selectively communicate with such Wireless Reader Tagsbased on physical distance from the Gateway.

Application Server communicates with nodes of ad hoc network through theexternal network and the Gateway to obtain and compile informationregarding tagged assets. In this respect, it now will be appreciated bythose having ordinary skill in the art that the nodes of theseClass-Based Networks comprise a distributed database of informationpertaining to the tagged assets. As set forth above, a Wireless ReaderTag or a Wireless Tag stores in memory not only a WRT ID or WT ID,respectively, but also may store additional information such as, forexample: class designation; sensor derived information; a prioritydesignation to provide improved response to selected broadcasts; aprivilege level; time-sensitive information; a characteristic of theparticular tagged asset; and/or a behavior of the tagged asset. Thisstored information becomes accessible by the asset-tracking applicationserver through the Classed Based Networks. The asset-trackingapplication server also can obtain the WRT ID associated with each WT IDfor intelligence gathering purposes.

Turning now to FIG. 1, a preferred embodiment of the present inventionis illustrated in a shipping environment 100 including a warehouse 104.A Wireless Reader Tag 110 (also represented by “LPRF” in the drawings)is attached to each pallet 120 in the shipping environment 100. Anactual implementation would involve thousands of pallets and LPRFs;however, for clarity only three pallets 120 and Wireless Reader Tags 110are shown in FIG. 1. Assets 134 on the pallets 120 each are tagged witha Wireless Tag 130 (also represented by “RFT” in the drawings).

Each Wireless Reader Tag 110 preferably is active, while each WirelessTag 130 preferably is semi-passive. As set forth above, passive WirelessTags 110 and Wireless Reader Tags 130 are devices that collect RF energyinductively and selectively respond, including sending information thatis stored thereon. These type of devices may be viewed as selectivereflectors of incident RF signals. Semi-passive and semi-active WirelessTags 110 and Wireless Reader Tags 130 are devices that use internalenergy, in the form of a battery, to power some portion of the circuitto either detect a transmission or make a transmission. Active WirelessTags 110 and Wireless Reader Tags 130 are devices that use internalpower, in the form of a battery, to both detect and make transmissions.

Preferably, both Wireless Tags 130 and Wireless Reader Tag 110 areread-write devices, but the Wireless Tags 130 may be read-only(generally characteristic of passive devices) within the scope of thepresent invention.

A Gateway 140 (also represented by “NIM” in the drawings) represents acommunication link between an external network (LAN) 150 and Class-BasedNetworks formed by the Wireless Reader Tags 110. The Gateway 140 is anexternal network access transceiver that comprises a radio base stationdirectly or indirectly connected to a wired network (e.g., usingEthernet, or wireless Ethernet). The radio base station portion ofGateway 140 is an LPRF-compatible module that communicates with WirelessReader Tags 110 of the Class-Based Networks. In essence, the Gateway 140links the Class-Based Network of the present invention with conventionalnetwork topologies that use conventional network protocols. The Gateway140 thereby facilitates monitoring, controlling, and querying WirelessReader Tags 110 and Wireless Tags 130 in the Class-Based Networks usingapplication software running on a server computer 160 connected to theexternal network 150. The server 160 may be operated on a generalpurpose computer, such as a personal computer, minicomputer, ormainframe.

A system in accordance with the present invention may include componentsin addition to those described above. For example, a Communicator 170(also represented by “HIM” in the drawings) and a mobile locatingGateway 180 (also represented by “MLG” in the drawings) are provided inthe preferred embodiment of FIG. 1. Communicator 170 is used to manuallyread class designations from network entities, such as Wireless ReaderTag 110 and Wireless Tags 130, and to assign class designations. Gateway180, which is installed in shipping vehicle 184, has the corecapabilities of a Wireless Reader Tag and a Gateway, plus at least twoadditional features. Gateway 180 includes a GPS receiver (not depicted)for determining geographic location of shipping vehicle 184 and a mobileinterface such as a cellular or satellite transmitter 186 fortransmitting data to server computer 160 via a mobile phone network 188.In implementation, the Communicator 170 and Gateway 140,180 each includea Wireless Reader Tag incorporated therein. Thus, because Gateway140,180 and Communicator 170 each includes the core hardware andsoftware of a Wireless Reader Tag, each can actively participate in theformation, control, and maintenance of the Class-Based Networks.

The operation of the CBNF routine of multiple Wireless Reader Tags inaccordance with the present invention for forming Class-Based Networksnow is described.

Network Formation

In accordance with the present invention, the CBNF routines of multipleWireless Reader Tags cooperate to propagate a distinct hierarchicalnetwork among each of multiple WRT Classes of the Wireless Reader Tags.To accomplish this class-based network formation, the WRT Class for eachWireless Reader Tag is stored in memory and included in the preamble ofeach network formation communication generated by the Wireless ReaderTag. The WRT Class may be identified by any series of codes orcharacters, the interpretation of which should be standardized and usedby all possible recipients of network formation communications(including all Wireless Reader Tags 110, Gateways 140,180, andCommunicator 170).

For example, a WRT Class may include a category/subcategory list such as“/Wal-Mart/Shipment_(—)123”, or a linked list representing relationshipsof various categories and subcategories defined in a profile of theWireless Reader Tag. Moreover, in this example, the WT Classes ofWireless Tags associated with a Wireless Reader Tag of the WRT Class“/Wal-Mart/Store_(—)290/Shipment_(—)123” could include “/Televisions/32in” and “/Televisions/27 in”, representing 32 inch televisions andtelevisions 27 inch televisions on a pallet (to which the WirelessReader Tag is attached) that is scheduled for inclusion with shipmentnumber 123 to Wal-Mart store number 290.

Alternatively, if Wireless Reader Tags 110 are not preprogrammed innon-volatile read/write memory with a WRT Class designation, a WirelessReader Tag 110 may acquire a class designation by reading WirelessReader Tags 110 or Wireless Tags 130 nearest to it, and then store theclass designation and other profile information in non-volatileread/write memory. Specifically, a WRT can acquire or “adopt” a classdesignation from a surrounding WRT or WT when that function is providedfor in the “profile” of the WRT. As used herein, a “profile” of a WRTincludes a list of attributes that invoke operating system functions,and can include information such as “adopted class.” If, for example, aWRT that is in a manufacturing area moves past a physical boundary thatputs it within a shipping area, then the WRT automatically adopts ashipping class for its previous manufacturing class. The classdesignations may look like this when in Manufacturing:/Sony/TV/24″/Manufacturing-Finishing/serial #10; and like this when inShipping: /Sony/TV/24″/Shipping/serial #10.

The value to this system is that as products are completed, the class ona pallet will not need to be manually changed because it automaticallyupdates according to location (i.e., near the shipping docks). The samemay happen once a driver leaves the parking lot and the radios no longercommunicate to a NIM, but now communicate with a MLG. In this case, theclass designations may look like this: /Sony/TV/24″/Intransit/ABCTrucking/serial #10.

Thus, when a pallet 120 is moved onto shipping vehicle 184, the pallet'sWireless Reader Tag 110 migrates to join a Class-Based Network headed byGateway 180. Gateway 180 then is able to report the migration toapplication server 160 via a network link that it has formed withGateway 140.

The WRT Class may also include other information concerning a status,characteristic, or privilege of the Wireless Reader Tag, the network, orother conditions. Virtually any profile information can be included inthe preamble and combined with class designation information to be usedfor network formation. Furthermore, the preamble information can berepresented in any convenient format, including various encodingschemes. In one embodiment, a Walsh code is assigned to each classdefinition and provided to Wireless Reader Tags of the class.

Walsh codes are well understood in the field of digital wirelesscommunications and, therefore, require only a brief explanation here.Walsh codes are used to encode data packets and to designate the classof Wireless Reader Tags that are enabled to receive and decode aparticular packet of data. The association of Walsh codes with classdesignation information facilitates reduced battery consumption inWireless Reader Tags by utilizing targeting methods requiring verylittle processing power. The use of Walsh codes also improves datasecurity by encoding of such communications. Those skilled in the artwill recognize that many other methods may be used for encoding classdesignation information in the preamble of data packets to facilitateclass-based network formation and network formation communications whilereducing battery consumption and RF interference.

FIG. 2 is a flowchart illustrating a preferred operation of the CBNFroutine in accordance with the present invention to form a Class-BasedNetwork. With reference to FIG. 2, upon power up, a first WirelessReader Tag of a predetermined WRT Class initially listens (Step 210) fortransmissions of other Wireless Reader Tags of the same WRT Class, whichwould indicate the presence of a Class-Based Network for such WRT Class.If such a Class-Based Network is detected, then the first WirelessReader Tag attempts to join (Step 220) the Class-Based Network as a“secondary” unit by issuing a registration request signal. Otherwise, ifno Class-Based Network is detected, then the first Wireless Reader Tagattempts join the overall network by establishing such a Class-BasedNetwork as a “primary” unit. This is done by transmitting (Step 230) a“primary_ready” signal to all other Wireless Reader Tags of the same WRTClass within the broadcast range of the first Wireless Reader Tag. Thefirst Wireless Reader Tag then listens (Step 240) for replies from otherWireless Reader Tags attempting to register as secondary units in thenew Class-Based Network.

If no reply for registration as a secondary unit is detected, and if theWRT Class of the first Wireless Reader Tag can be abstracted, then theWRT Class is abstracted (Step 250) by truncating the class designation.For example, if the initial WRT Class is“/Wal-Mart/Store_(—)290/Shipment_(—)123”, then the class designation isabstracted to “/Wal-Mart/Store_(—)290”. The process then repeatsstarting at Step 210 for this abstracted class designation as the newWRT Class for the first Wireless Reader Tag. If this process continuesto repeat, the class designation will not be able to be abstractedfurther without otherwise being generic to all classes of WirelessReader Tags, i.e., WRT Class being “/”. At this point, the firstWireless Reader Tag attempts to connect (Step 294) to a Gateway (“NIM”in FIG. 2) and register as a member of the WRT Class that is the highestabstraction possible without being generic to all Wireless Reader Tags(i.e., as a member of the root class “/Wal-Mart”). Upon successfulregistration with the Gateway, the first Wireless Reader Tag then enters(Step 296) sleep—or standby—mode to conserve battery power.

If a reply from a secondary unit is detected, then the first WirelessReader Tag registers (Step 260) the secondary unit and repeats theregistration for each reply from other secondary units until adetermination is made (Step 270) or until no more such replies aredetected. A “cluster” in this context comprises a primary unit and thesecondary units with which the primary communicates directly, and may belimited in number of units by the number of communication channels thatcan be supported by the primary unit operating as a cluster head. Once acluster is full, the first unit (cluster head) responds to the nextsecondary unit attempting to register by promoting (Step 280) it to thestatus of a primary unit. The first Wireless Reader Tag—now the clusterhead of the full cluster—then attempts to register (Step 290) with thenewly promoted primary unit as one of its secondary units. The newprimary unit, in turn, then is available to serve as a cluster head forother Wireless Reader Tags, to promote other Wireless Reader Tags tohigher level primary units, and so forth, thereby propagating ahierarchical Class-Based Network from the “bottom-up.” The firstWireless Reader Tag and the other Wireless Reader Tags form theClass-Based Network using the same CBNF routine.

Returning to Step 270, if the cluster of the first Wireless Reader Tagdoes not completely fill, if no more first Wireless Reader Tags attemptto register as secondary units, and if the first Wireless Reader Tag hasa class designation that is other than its root class, then the firstWireless Reader Tags abstracts its WRT Class (Step 250) by truncatingthe class designation and starts over the entire CBNF routine beginningat Step 210 (i.e., listening for the presence of Wireless Reader Tags ofthe truncated class at Step 210, etc.). Note that in accordance withpreferred embodiments of the present invention, a Wireless Tag orWireless Reader Tag will respond if its class is identified in acommunication, even if the class in the communication is abstracted.Thus, a Wireless Tag or a Wireless Reader Tag having a class designationof “/sony/tv/color/24” will respond to a communication identifying theclass as “/sony/tv” as its class (i.e., its abstracted class) isidentified in the communication.

If no other Wireless Reader Tags are attempting to register and if thefirst Wireless Reader Tag's WRT Class cannot be abstracted, then thefirst Wireless Reader Tag attempts to register (Step 294) with theGateway and, thereafter, enters (Step 296) into an idle mode.Alternatively, the first Wireless Reader Tag may start attempting toregister with the Gateway soon after it becomes a primary at Step 230 orconcurrently with filling its cluster at Step 270. Furthermore, whenpromoting a Wireless Reader Tag to a primary unit, the first WirelessReader Tag would also pass to the promoted Wireless Reader Tag theresponsibility for connecting with the Gateway on behalf of the cluster,if possible.

In accordance with the Bluetooth standard, the Gateway will be able tocommunicate with seven other WRTs simultaneously. However, the targetedWRT Class can revolve on each channel as a function of time in order toaddress multiple WRT Classes on the single channel. Upon registrationwith the Gateway, the system may establish a revolving communicationschedule with revolving class addressing that allows the Gateway tocommunicate with hundreds or thousands of WRT Classes on the channel.Synchronization between the Gateway and Wireless Reader Tags isimportant for proper operation of revolving class addressing and tominimize battery consumption. Accordingly, as WRT Classes are added tothe overall network and establish communication with a Gateway, theGateway may synchronize, reconfigure, and optimize the WRT Class′schedule for revolving class addressing.

The Class-Based Networks also are reconfigurable in response to changesin the location, status, behavior, characteristics or class designationassociated with the Wireless Reader Tags. For example, assets of a class(e.g., in-production) can be selectively transferred to a new class(e.g., shipping) by merely changing the WRT Class designation with whichthe assets are associated. Class-Based Networks also facilitate the useof asset-tracking applications and process flow controls to track andmanage the assets based on real-world requirements, such asmanufacturing requirements, shipment, warehouse management, zonecontrol, environmental impacts, etc. Class-Based Networks alsofacilitate automated segregation and delivery of assets.

In a “top-down” CBNF routine, illustrated in FIGS. 12-21, when a clusteris filled the secondary units that have already registered with thefirst Wireless Reader Tag (the cluster head) may be promoted to assumethe role of middle-hierarchy primary units, called “sub-primaries.”Sub-primaries, which continue as secondary units below the firstWireless Reader Tag (cluster head), then provide connectivity for anyadditional Wireless Reader Tags that are attempting to join theClass-Based Network in clusters headed by the sub-primaries.

In both the top-down and bottom-up methods, secondary units promoted bythe first Wireless Reader Tag become new cluster heads that, themselves,may provide connectivity to Wireless Reader Tags of the same WRT Classthat are beyond the actual transmission range of the first WirelessReader Tag. The Wireless Reader Tags thereby collectively form ahierarchical, multi-tiered network based on class designation thatpropagates both in quantity of nodes and geographic coverage. Tightlygrouped Class-Based Networks formed in accordance with the presentinvention thus make it possible to communicate to and among a particulartarget class of Wireless Reader Tags without requiring messages to bereceived, processed, or routed by Wireless Reader Tags that are notmembers of the target WRT Class or an abstracted Class thereof. Thishierarchical Class-Based Networks is an efficient topology forcommunicating among Wireless Reader Tags of the same WRT Class, becauseit reduces the number of network nodes through which messages must passand, consequently, thereby significantly reduces RF interference andbattery power consumption otherwise experienced.

FIGS. 3-11 depict Wireless Reader Tags in a time-sequence of eventsshowing a bottom-up method of the CBNF routine. With reference to FIGS.3-11, Wireless Reader Tags 1-6 and Wireless Reader Tags A-G are membersof WRT Classes “circle” and “triangle,” respectively, which arearbitrary class designations assigned for purposes of illustration only.In this example, the Wireless Reader Tags 1-6 and Wireless Reader TagsA-G operate on up to three communication channels and one generalchannel (also called the control channel). The Wireless Reader Tags allinclude CBNF routines operating in accordance with the method shown inFIG. 2.

The CBNF routine of each Wireless Reader Tags 1-6 and Wireless ReaderTags A-G is configured to initially listen for a communication having adata packet with a preamble that identifies a Wireless Reader Tag of thesame WRT Class as the Wireless Reader Tag executing the CBNF routine(see FIG. 2, Step 210). In this example, the preamble of each packet isrepresented by a colon-separated string of information, asfollows::Target Class:My Profile:Action Requested:Target Cluster Head ID, where “Target Class” is the WRT Class of Wireless Reader Tags directedto wake up from standby to receive and process the data packet. In thisexample, the Target Class is either “/circle” or “/triangle” (there areno subcategories in this example). However, in a more complex embodiment(not shown) the Target Class designation could include subcategoryinformation in a slash-separated list, in a linked list, with Walshcodes, or by any other method of representing category and subcategoryinformation. The “My Profile” section of the preamble identifies theWireless Reader Tag transmitting the communication by WRT Class and WRTID unique to the Wireless Reader Tag. The “Action Requested” includesthe message, and the “Target Cluster Head ID” identifies the WirelessReader Tag of the cluster head or proposed cluster head, if any.

Thus, for example, with reference to FIG. 3, after listening for datapackets of its WRT Class (i.e., /circle) and detecting none, WirelessReader Tag 1 attempts to start a Class-Based Network for the WRT Classof “/circle” as a primary unit by transmitting a data packet having thefollowing preamble::/circle:/circle/unit 1: primary_ready:no primary.

The class designation “/circle” causes only Wireless Reader Tags of theWRT Class “/circle” to receive and process the message of the datapacket. Wireless Reader Tag 1, if it receives no replies, may retransmitthe communication multiple times before timing out and beginning abeacon procedure or entering a battery-saving lost mode. Furthermore,the data packets (and others described below) may encapsulate a datapayload or may have a null payload.

Wireless Reader Tags are preferably synchronized to allow scheduledcommunication to a particular WRT Class at regular intervals. When anWireless Reader Tag communicates to a target WRT Class, the WirelessReader Tag transmits a data packet at a time precisely synchronized withthe targeted WRT Class. To conserve battery power, the receiving membersof the WRT Class only power up to listen at each such interval and onlyfor very small periods of time (e.g., a few milliseconds) when datapacket for such WRT Class would normally be transmitted. The intervalsat which a Wireless Reader Tag listens for communications directed toits WRT Class is called the duty cycle, which can be dynamicallyadjusted to respond to network communication demands while minimizingbattery consumption. Depending upon the time sensitive nature of theassets being tracked and their priority, a period of inactivity mayprompt a Wireless Reader Tag to limit its duty cycle to intervals ofminutes or hours. After a prolonged period of inactivity, a WirelessReader Tag may ping (transmit) to determine whether other WirelessReader Tags are still alive and available for communication. Assumingthat no network changes have occurred, the Wireless Reader Tag goes backto sleep until the next duty cycle. Network changes may cause all or apart of a Class-Based Network to reconfigure.

With reference to FIG. 4, in response to the “primary_ready” signal,Wireless Reader Tags of WRT Class “/circle” within range of WirelessReader Tag 1 respond with a registration request signal, as listed inTable 1 of FIG. 26.

Because the registration request packets include in their preambles atarget WRT Class of Wireless Reader Tag 1, only Wireless Reader Tag 1will wake up from standby to receive and process the registrationrequest packets. The transmitters of Wireless Reader Tags 2-6 wouldpreferably include conventional collision avoidance routines to avoidinterfering transmissions of the registration request packets, as setforth by the Bluetooth specifications.

With reference to FIG. 5, in response to receipt at Wireless Reader Tag1 of the registration_request signals from Wireless Reader Tags 2-6, theCBNF routine of Wireless Reader Tag 1 registers and acknowledges thesecondary Wireless Reader Tags to form a cluster. In this example,Wireless Reader Tag 1 has a maximum cluster capacity of three secondaryunits. Consequently, it only registers and acknowledges the threeWireless Reader Tags from which the strongest registration requestsignals are received which, in this example, are Wireless Reader Tags2-4. (Note that the ability of a LPRF device to determine signalstrength is conventional and, therefore, is not described in detailherein.) By registering and acknowledging secondary units on the basisof signal strength, rather than on a first-come-first-served basis orsome other basis, the CBNF routine establishes a cluster that is energyefficient for communication within the cluster. To acknowledgeregistration of the secondary units, Wireless Reader Tag 1 transmits anacknowledgement signal to the Wireless Reader Tags 2-4, as set forth inTable 2 of FIG. 27.

The network topology is now shown in FIG. 6 and the cluster hierarchy isdepicted in FIG. 6A. The two concentric circles of Wireless Reader Tag 1indicate that it is a cluster head at Level 2 in the network hierarchy.

With reference to FIG. 7, with its cluster capacity now exceeded,Wireless Reader Tag 1 (the cluster head) selects from the other WirelessReader Tags attempting to register the unit having the strongestregistration request signal (in this example Wireless Reader Tag 5) anddirects such unit to become a new primary unit. The new primary unitthen serves as a new cluster head for a cluster in which Wireless ReaderTag 1 becomes a secondary unit (thus the “bottom-up” description of themethod). In this example, the command from Wireless Reader Tag 1 toWireless Reader Tag 5 is: /circle/unit5:/circle/unit1: promote_andrequest_primary: no primary.

With reference to FIG. 8, Wireless Reader Tag 5 acknowledges thepromotion signal from Wireless Reader Tag 1 and begins to propagate theClass-Based Network at the next higher level in the hierarchy, which nowhas three levels as depicted in FIG. 8A. In acknowledging its promotionand registration as a primary to Wireless Reader Tag 1, Wireless ReaderTag 5 transmits its acknowledgement packet to all units of its classwithin range, by the following preamble::/circleicircle/unit5:primary_acknowledged:/circle/unit5.

By transmitting to all units of its WRT Class within range, WirelessReader Tag 5 efficiently registers with Wireless Reader Tag 1 andconcurrently shares primary status information with all Wireless ReaderTags of its WRT Class within its broadcast range (which is differentfrom the broadcast range of Wireless Reader Tag 1). The three concentriccircles around Wireless Reader Tag 5 indicate that it is a primary inthe third-level of the hierarchy of the Class-Based Network.

With reference to FIGS. 9 and 9A, Wireless Reader Tag 6, upon receivingWireless Reader Tag 5's registration acknowledgement (FIG. 8), requeststo register as a secondary unit to Wireless Reader Tag 5 by sending apacket with the followingpreamble::/circle/unit5:/circle/unit6:request_primary:/circle/unit5.

To which, unit 5 responds with::/circle/unit6:/circle/unit5:registration_ackn:/circle/unit5

This exchange results in the hierarchy shown in FIG. 9A.

With reference to FIG. 10, a Class-Based Network for the WRT Class“/triangle” is similarly formed by Wireless Reader Tags A-G concurrentlywith the steps shown in FIGS. 3-9, whereby two distinct hierarchalClass-Based Networks result as shown in FIG. 10A.

With reference to FIG. 11, if a Gateway is available, the highest levelprimary units (Wireless Reader Tags 5 and A in this example) registerwith the Gateway to establish connectivity to an external networkincluding an application server (no shown) communicating therewith.

FIGS. 12-21 illustrate another preferred top-down CBNF routine in whichthe Wireless Reader Tags transmit a series of network formationcommunications in the course of self-organizing a hierarchical network,the topology of which is shown at various stages adjacent to FIGS. 13,16, 19, and 21 in respective FIGS. 13A, 16A, 19A, and 21A. As with FIGS.3-11, the transmitting Wireless Reader Tags are shown in heavy boldoutline, but the hierarchical levels are not indicated this time byinner circles and triangles.

With reference to FIG. 12, a first Wireless Reader Tag 1 wakes up andreads profile information stored in its memory, including a predefinedclass designation of “/circle” as its WRT Class. This profile is storedinto the memory of the Wireless Reader Tag 1 during an initialization ofthe Wireless Reader Tag 1. Based on this class designation, WirelessReader Tag 1 then listens for transmission activity by other WirelessReader Tags of the same WRT Class. If the nearby Wireless Reader Tags ofthe WRT Class have already formed a Class-Based Network for “/circle”accordance with the present invention, then Wireless Reader Tag 1attempts to join such Class-Based Network. Otherwise, Wireless ReaderTag 1 attempts to organize a Class-Based Network for such WRT Class.

To begin organizing Class-Based Network, Wireless Reader Tag 1 transmitsa primary_ready signal including its designated WRT Class. As in theCBNF routine described above in FIGS. 3-11A, the primary_ready signal ispreferably a data packet that includes in its preamble datarepresentative of the “circle” class designation. In FIG. 12, the boldboundary of Wireless Reader Tag 1 indicates that it transmits ratherthan receives. The range of the transmission is depicted by dashedcircle “R.” Nearby Wireless Reader Tags 2-5 and B, C, D, and E, whichare within range of the primary_ready signal, each processes only thepreamble portion of the primary_ready signal to determine whether thetransmission if from a Wireless Reader Tag of the same WRT Class. Byfirst processing only the preamble portion of the primary_ready signal,battery power is conserved in triangle Wireless Reader Tags B, C, D, andE. If it is of the same class, then the receiving Wireless Reader Tag—inthis example, each of Wireless Reader Tags 2-5—wakes up, receives, andprocesses the entire primary_ready signal, and then responds as shown inFIG. 13 and described below.

With reference to FIG. 13, each of the Wireless Reader Tags of the WRTClass “/circle” that received the primary_ready signal in FIG. 12 (i.e.,units 2-5) responds to the primary_ready signal with a registrationrequest signal. Upon receipt of the registration request signal,Wireless Reader Tag 1 assumes the status of a primary unit, whileWireless Reader Tags 2-5 assume the status of secondary units. FIG. 13Ashows the resulting 2-tiered network hierarchy tree representative ofthe Class-Based Network thus formed between Wireless Reader Tags 1-5.

Next, with reference to FIG. 14, a third tier of the hierarchicalnetwork is formed by Wireless Reader Tag 6. In this regard, WirelessReader Tag 6 was out of range of Wireless Reader Tag 1's primary_readysignal shown in FIG. 12, but is within range of the registration requestof Wireless Reader Tags 3 and 5 shown in FIG. 13. Wireless Reader Tag 6,which was listening during the step shown in FIG. 13, received theregistration request signals of Wireless Reader Tags 3 and 5 becausethose signals included the “/circle” class designation matching the“circle” class designation of Wireless Reader Tag 6. The registrationrequest signals indicate to Wireless Reader Tag 6 the presence of anearby Class-Based Network of corresponding WRT Class, which causesWireless Reader Tag 6 to transmit a request to join this Class-BasedNetwork.

Concurrently with the ongoing formation of the “/circle” class network,FIG. 14 also depicts the beginning stages of the formation of aClass-Based Network for the WRT Class of “/triangle” by Wireless ReaderTags A-G. In this regard, Triangle Wireless Reader Tag A wakes up andlistens for the presence of a “/triangle” class network. Detecting noother “/triangle” WRT Class signals, Wireless Reader Tag A transmits aprimary_ready signal, similar to the transmission of Wireless Reader Tag1 shown in FIG. 1, but with a “/triangle” class designation forming partof the preamble of the primary_ready signal.

With reference to FIG. 15, triangle class Wireless Reader Tags B, C, andD receive the primary_ready signal of Wireless Reader Tag A and respondwith registration request signals, thereby forming a second hierarchalClass-Based Network, as shown in FIG. 16A.

Also shown in FIG. 15, circle Wireless Reader Tags 3 and 5 respond tothe request to join of Wireless Reader Tag 6 of FIG. 14 withprimary_ready signals. Wireless Reader Tag 6 then responds to thestrongest primary_ready signal received (in this example, the signalfrom Wireless Reader Tag 5), with a registration request. WirelessReader Tag 6 thereby forms a third tier of the Class-Based Network for“/circle” WRT Class, also as shown in FIG. 16A.

With reference to FIGS. 17-19, Wireless Reader Tags E, F, and G of theWRT Class “/triangle” each joins the Class-Based Network for trianglesformed by Wireless Reader Tags A, B, C, and D.

FIGS. 20-21A illustrate the completion of the Class-Based Networks withthe registration with the Gateway of the highest primary unit in eachClass-Based Network hierarchy.

As will now be apparent to one having ordinary skill in the art, inconjunction with the asset-tracking application server, Class-BasedNetworks facilitate automated and semi-automated segregation, tracking,monitoring, and delivery of assets. The server issues, via the Gateway,class-directed messages to monitor and track WRT Classes. User-definedclass granularity facilitates the use of separate categories and/orsubcategories for various attributes and states of the assets, e.g.,production batches, phases of production, and the delivery process. Byincreasing granularity, i.e., using many categories or subcategories(including sub-subcategories and so on), messages or otherclass-directed communications from the application server can bedirected to only those classes of interest representing such categories,subcategories, or sub-subcategories, as desired. Furthermore, becausemessages or other class-directed communications are transmitted inpackets that specify class designations for intended transceiverrecipients, only those transceivers that are members of the specifiedclass awaken from standby mode to receive and process the packets, andthen to acknowledge or reply thereto as appropriate. Accordingly, thisreduces RF interference and power consumption otherwise experienced,while making asset-tracking functions more efficient.

Once established, the Class-Based Networks provide functionality as adynamic distributed hierarchical database system. In this regard,Wireless Reader Tags and Wireless Tags preferably include a handlingroutine in communication with a memory of the Wireless Reader Tags andWireless Tags. The handling routine interprets and responds toclass-directed database commands, e.g., data queries or data updatesfrom an asset-tracking application or a Communicator. Database queriesmay include status queries that provide the asset-tracking applicationwith real-time up-to-date status information about tagged assets. Dataupdates may include requests to change data maintained on specifiedWireless Reader Tags of the distributed database system. Similar tonetwork formation communications, class-directed database commandsinclude preambles that identify a WRT Class of Wireless Reader Tags towhich they are directed. In this manner, only those Wireless Reader Tagsof the selected class need process the database command. Class-directeddatabase commands may also include, in their preambles, a wildcard thatindicates to query handling routines that all Wireless Reader Tags of aparticular abstracted WRT Class should receive and process the databasecommands. Class-directed commands thereby avoid unnecessary radiointerference and reduce power consumption by Wireless Reader Tags thatare clearly outside the scope of the database search criteria. Databaseperformance is also enhanced by selecting Wireless Reader Tag classesand class abstractions in a way that mirrors a preferred hierarchicalstructure for the data they contain. In this way, increased classgranularity facilitates improved data retrieval efficiency in thedistributed database system by reducing the number of Wireless ReaderTags that must be involved in a database query or update transaction.The Class-Based Networks themselves act as a hierarchical databasefacilitating fast and efficient database queries.

The CBNF routine used to form the Class-Based Networks in accordancewith the present invention may also be used to perform autonomousmodification and reconfiguration of such networks in response to changesin the location, status, behavior, characteristics or class designationof Wireless Reader Tags and/or Wireless Tags. Similarly, theself-configuration methods of the present invention facilitatemaintenance of radio communication links in response to changes in theoperational characteristics of the Wireless Reader Tags and/or WirelessTags that comprise the network fabric. For example, self-configurationroutines are responsive to changes caused by battery drain, radiotransmitter failures, radio interference, and digital processor failure,by their inherent methods of organizing the network to have optimal linkintegrity and node connectivity.

Functions/Commands

The following functions preferably are supported in an Wireless ReaderTag of the present invention—and in a Wireless Tag, where indicated—toaccomplish the aforementioned class-based network formation andsubsequent reformation. The name of the function is followed by thedescription of the function in the context of the type of transceiver inwhich it is to be implemented, i.e., Wireless Reader Tag and/or WirelessTag.

Acquire Class or Sub-Class Structures

Software on the Wireless Reader Tags and Wireless Tags interpretscategory and subcategory structures represented by WRT and WT Classes,respectively. To initialize, the Wireless Reader Tags arbitrarily formnetworks based on the ability to talk to other Wireless Reader Tags.When a Wireless Reader Tags wakes up it broadcasts a message to otherWireless Reader Tags that it is a primary unit seeking secondary units.Other Wireless Reader Tags awaken to receive the message and attempt toregister with the primary unit. If they are unable to communicate withthe primary unit, or if the primary unit's cluster is full, then thesecondary units will attempt to become a primary unit and continue theprocess. Once Wireless Reader Tags have established a network, thehighest primary unit of the hierarchy contacts the Gateway andcommunicates with the application server, whereupon a profile isdownloaded to the primary unit and passed on to each Wireless Reader Tagof the network. The profile downloaded is based on options such asreading Wireless Tags, WRT IDs, business rules located at theapplication server and other information that has been downloaded by aCommunicator. For example, and with regard to a WRT, the profile is alist of attributes or “personalities” assigned to each WRT. The list inthe profile will be determined by business rules (like “things move intothe shipping are ready to be shipped”, “all fresh meat shipments mustleave the plant within 24 hours of packing”, etc.); a Communicator(used, for example, by a supervisor who views the asset and determinesthat it needs another coat of painting and manually changes the classback to “pre-paint step”, etc.); and server application (firsttwo-hundred assets shipped to New Jersey, next two-hundred assetsshipped to Florida, last five-hundred assets shipped to California,etc.). The profile function can allow conditional class change.

Once the Wireless Reader Tags have their respective profiles, theWireless Reader Tags reform in Class-Based Networks based on rulesdefined by the software located on the Wireless Reader Tags. Ifread-only Wireless Tags are used, then the WR Class can bepre-programmed into the Wireless Tags but will not be able to bemodified dynamically. The dynamic acquisition of a WRT Class is based onrules defined by the application server.

Allow Class/State Change

Class changes are allowed based on business rules setup by the customerto track and group their assets. The rules are built into the serverapplication and the software on the Wireless Reader Tags. The profileprovides information that allows dynamic decisions to be made by theWireless Reader Tags. Once the Wireless Reader Tags have determined thattheir category, subcategory, etc. as represented by their WRT Class haschanged, the Wireless Reader Tags must join the new WRT Class. Theability to allow such a class change provides functionality to allowdynamic changes to WRT Class by a Wireless Reader Tag. For example, withreference to FIGS. 10 and 10A, changing the WRT Class of the WirelessReader Tag E to “circle” from “/triangle” causes Wireless Reader Tag Eit to join the Class-Based Network for the circle, either as a secondaryunit in a cluster of an existing primary unit (e.g., circle WirelessReader Tag 5), or by becoming a primary unit itself. Continued contactbetween Wireless Reader Tag E and the WRT Class of triangles could belimited based on system rules, but preferably is terminated. In anexample of this, the WRT class of triangles could represent goods in theprocess of being manufactured in a factory. When these goods enter ashipping section of the factory, the Wireless Reader Tags associatedwith the goods on the pallet would automatically acquire a “shipping”WRT Class representative of their current location and associated statusin shipping.

Form Class

A Class-Based Network for a new class can be established by downloadinga new profile and using the command “Determine Primary”. The commandthen uses techniques in FIGS. 2-21 to establish the Class-Based Networkfor the new class. Profiles and software on the Wireless Reader Tagsform the basis for decisions on network formation. The profile must bepreprogrammed in the Wireless Reader Tags or Wireless Tags or downloadedfrom the application server.

Combine Classes

The combination of classes is required when the user no longer wishes todifferentiate between two originally defined classes. The profile isdownloaded either as a new class profile that has a new class name ordownloads to the class to be replaced by the other existing class. Aftercombining classes, the Wireless Reader Tags may reform the network usingthe CBNF routines of the present invention.

Determine Primary

When a Wireless Reader Tag “wakes up”, it determines whether it is ableto become a primary unit with the determine primary command. If thehealth of the device is sufficient, it sends out a message to otherWireless Reader Tags of its WRT Class for registration of secondaryunits.

Ping MLG/Gateway/Communicator

A Wireless Reader Tag incorporated into a MLG, Gateway, or Communicatorsends out a special message identifying itself as part of an MLG,Gateway, or Communicator. The purpose of this message is to inform otherWireless Reader Tags in stand-alone mode that the Wireless Reader Tagincorporated into the MLG, Gateway, or communicator has additionalcapabilities. The identifying message allows the Communicator to queryinformation from the Wireless Reader Tags or Wireless Tags while themessage from the Gateway and MLG indicate an ability to communicate tothe external network.

Inventory WT Tags

The Wireless Reader Tag will read all Wireless Tags within range. Theprofile downloaded from the application server will help the WirelessReader Tag control misreads and extra tags. Multiple reads of the tagsinsures high reliability.

Report Communication Links

Upon formation of a Class-Based Network, a Wireless Reader Tag storesidentifiers that describe the Wireless Reader Tags constitutingneighbors in adjacent levels of the network hierarchy. The primary unitthus will store all the WRT IDs for its secondary units, while thesecondary units will store the WRT IDs on the primary unit and anysecondary units thereto. The knowledge of communication links, bothupstream and downstream, supports responsiveness to queries from theapplication server.

Report Local Classes

By listening for preambles of data packets intended for other classes,Wireless Reader Tag may store WRT Class information about other WirelessReader Tags in their vicinity. The Wireless Reader Tags will supportqueries from the application server to supply this intelligenceregarding local class information, regardless of whether the reportedclass even maintains connectivity to the application server.

Class Structure-Secondary Only

The secondary only command provides entry into a system without givingnetwork formation rights. In this regard, the Wireless Reader Tag withthis designation in the profile is allowed to act like the othersecondary Wireless Reader Tags, but it is unable to take on the role ofa primary unit and, thus, is itself restricted from further propagatingthe network. This allows the Wireless Reader Tag the ability to movefrom one WRT Class to another WRT Class without otherwise disturbing thehierarchy of each Class-Based Network of which it becomes a part. Apractical of this command enables a customer, who walks into a warehouseretailer, to read product names, costs, or locations in the storewithout interrupting or disturbing the resident asset-trackingapplication.

Server Assisted Network Formation

The CBNF routines described above with reference to FIGS. 3-11 and 12-21involved peer-centric network formation, in which Wireless Reader Tagsself-formed an ad hoc Class-Based Network and then contacted anapplication server via a Gateway. In this peer-centric method, eachWireless Reader Tag contains software that is preprogrammed to interpretclass information contained in the preamble of messages beingtransmitted by other Wireless Reader Tags and then negotiate to be aprimary unit. The Wireless Reader Tags use commands such as inventoryWireless Tags, determine primary, and others (described above) to makedecisions on class and other profile information that has beenpreprogrammed in the Wireless Reader Tags. Once the Wireless Reader Tagshave formed the Class-Based Network, information is transmitted by theWireless Reader Tags for connectivity to server applications.

Other network propagation methods within the scope of the presentinvention are contemplated, and include a server-initiated method and aclient/server shared method. In the server-initiated method, theWireless Reader Tags are attached to pallets or areas to readinformation from Wireless Tags. The Wireless Reader Tags are turned onand first form an arbitrary network using commands such as DeterminePrimary. This arbitrary formation is done so that the server can addressparticular Wireless Reader Tags, and the formation is not based on classdesignations. The Wireless Tags are read by the Wireless Reader Tags andprofiles are downloaded to the Wireless Tags from the Wireless ReaderTags based on commands such as “Inventory RF Tags”, described above.Profiles defining a new class structure are then downloaded from theserver to the Wireless Reader Tags (and any read/write Wireless Tags)based on business rules. The Wireless Reader Tags are then instructed toDetermine Primary again, whereby Class-Based Networks are formedaccording to the newly-assigned class structure. In this regard, theprofiles are lists of options that the Wireless Reader Tag can use tomake decisions. For example, if a pallet has TVs on it and the profilelists possible products as VCRs, TVs, Cameras and Unknown, then theWireless Reader Tag knows to adopt the class of TVs and form a networkaccordingly. If TV was not in the list, then the Wireless Reader Tagcould adopt the class Unknown and generate a system flag for furtheranalysis.

In the client/server shared method, the Wireless Reader Tags are loadedwith software preprogrammed to interpret profile information. Theprofile information may include WT IDs, states, and the like. TheWireless Reader Tags then are reset and boot up looking to read thesaved profile, to form hierarchical networks based on class designationsspecified in the profile, and to look for primary/secondaryconfigurations. Once the Wireless Reader Tags have setup the initialnetwork, network server business rules are downloaded to the WirelessReader Tags in the form of new profiles to “fine tune” the network. Inthis regard, general information about how a particular businessoperates is used to setup the network. Not enough information is known,however, about the assets. In this case, information can be stored inthe Wireless Tags as they are attached to the assets, and profiles inthe Wireless Reader Tags can enable the Wireless Reader Tags to readthis information and make intelligent decisions about how to efficientlysetup the network so that the data is an organized within the databasein a performance-enhancing fashion.

The following are examples of asset-tracking applications within thescope of the present invention.

Example 1 Tagged Luggage System

When a passenger checks in at the airport a Wireless Tag is attached toeach item of the passenger's luggage. A corresponding Wireless Tagidentifying the passenger is provided to the passenger to verify his/heridentity at the destination baggage pickup location. A Wireless ReaderTag near the check-in counter detects and logs the Wireless Tags for theluggage in association with the passenger's Wireless Tag and relatedinformation into the asset-tracking system. The asset-tracking systemdownloads a profile into each of the Wireless Tags as identified by theWireless Reader Tag at the check-in counter. The profiles are in theformat::Tag_Type Airline_Name:PassengerClass:Origin_and_Destination:Flight_No: Tag_Status:passenger_id. Anexample of the profile for the passenger's Wireless Tagis::passenger:Delta_Airlines:First_Class:ATL-SEA:FLT-490:check-in:4556778-8KDKO8; while an example of the profile for the luggage Wireless Tagis::baggage:Delta Airlines:FirstClass:ATL-SEA:FLT-490: check-in:45567788KDKO8.

Upon successful check-in, the luggage is placed on the conveyer beltwhere it is read by another Wireless Reader Tag. By way of acommunication from the Wireless Reader Tag, the profile of each WirelessTag on the luggage then is modified by altering the Tag_Status fieldfrom “check-in” to “luggage-transfer_station_(—)4334,” which identifiesa location of the Wireless Reader Tag at the conveyor belt. MultipleWireless Reader Tags are positioned along the conveyer belt system toidentify the specific area of location of the luggage as it progresses.Trucks that deliver the luggage to the plane also have Wireless ReaderTags attached to the truck and alter the Tag_Status to“departure_on-transfer-truck-1441”. Once the luggage is placed on theplane, yet another Wireless Reader Tag detects and logs the Wireless Taginto the asset-tracking system, whereupon a cross-check is made of theluggage as identified by the WT IDs with the luggage that is supposed tobe on the plane. Any luggage that is not supposed to be on the plane isflagged for removal by the asset-tracking system and rerouted to itsproper destination. Any luggage that is not accounted for raises analarm, so that attendants are alerted to its arrival time, its position,or its last known position and an investigation can be made.

Once the plane arrives at its destination, the Wireless Tags of theluggage are detected and logged in by an Wireless Reader Tag and theTag_Status field of each Wireless Tag is changed to“arrival_on-transfer-truck-6633”. At the destination baggage pickup, theWireless Tags on the luggage are read by a Wireless Reader Tag locatednear an exit of the baggage area. The Wireless Reader Tag detects andlogs the luggage Wireless Tags in association with the Wireless Tag ofthe passenger claiming the luggage, whereupon the asset-tracking systemassures that the passenger claiming the luggage is authorized to do so.A passenger inadvertently selecting the wrong luggage may then bealerted to the error.

Example 2 Warehouse/Retail System

A warehouse store such as Costco carries hundreds of brands of products.Nevertheless, all products need to be inventoried on a real-time basis.In accordance with the present invention, a Wireless Reader Tag isattached to each pallet of goods and assigned a class designation thatdenotes the manufacturer of goods on that pallet (e.g., Pillsbury, Sony,Kellogg's, etc.). Each Wireless Reader Tag may also include in its classdesignation or profile, information about the goods on the pallet. Eachboxes on the pallet carries a Wireless Tag that is read by the WirelessReader Tag of the pallet. On demand, each Wireless Reader Tag gathersinformation about the Wireless Tags on its pallet and relays theinformation back to the asset-tracking application server. At any giventime, an employee of the warehouse store can inventory goods of aselected manufacturer by sending a query that will be received only byWireless Reader Tags of the selected class corresponding to suchmanufacturer. Messages directed to a selected class will not appreciablyaffect the battery life of Wireless Reader Tags of other classes, asonly Wireless Reader Tags of the selected class will wake up fromstandby mode to receive the messages and process the query. Themanufacturer classes can be divided further into categories andsubcategories, thereby further collectively reduce battery consumptionand radio interference.

Example 3 Shipping Containers Tracking System

Containers full of material shipped via rail or ship can be received andlogged into a yard by manufacture based on class information stored onWireless Reader Tags. The Wireless Reader Tags form a network with othercontainers from a particular manufacturer and allow quick and efficienttracking of containers. Messages directed to a selected class will notaffect the battery life of Wireless Reader Tags of other classes becauseonly Wireless Reader Tags of the selected class will wake up fromstandby to receive the messages and process the queries. Themanufacturer classes can be divided into categories and subcategories,thereby further collectively reduce battery consumption and radiointerference.

Example 4 Manufacturing and Supply Chain Tracking System

A computer manufacturer may track the status of its supply chain inaccordance with the asset-tracking application of the present invention.The classes defined are “raw material,” “component stuffing,” “monitorassembly,” “final assembly,” “shipping,” “in transit,” and“distributor.” The manufacture can inventory raw material throughout theprocess by addressing the raw material class, and can find out where inthe manufacturing process the computer has reached by addressing monitorassembly or final assembly classes.

In view of the foregoing detailed description of preferred embodimentsof the present invention, it readily will be understood by those personsskilled in the art that the present invention is susceptible of broadutility and application. While various aspects have been described inthe context of arborist uses, the aspects may be useful in othercontexts as well. Many embodiments and adaptations of the presentinvention other than those herein described, as well as many variations,modifications, and equivalent arrangements, will be apparent from orreasonably suggested by the present invention and the foregoingdescription thereof, without departing from the substance or scope ofthe present invention. Furthermore, any sequence(s) and/or temporalorder of steps of various processes described and claimed herein arethose considered to be the best mode contemplated for carrying out thepresent invention. It should also be understood that, although steps ofvarious processes may be shown and described as being in a preferredsequence or temporal order, the steps of any such processes are notlimited to being carried out in any particular sequence or order, absenta specific indication of such to achieve a particular intended result.In most cases, the steps of such processes may be carried out in variousdifferent sequences and orders, while still falling within the scope ofthe present inventions. Accordingly, while the present invention hasbeen described herein in detail in relation to preferred embodiments, itis to be understood that this disclosure is only illustrative andexemplary of the present invention and is made merely for purposes ofproviding a full and enabling disclosure of the invention. The foregoingdisclosure is not intended nor is to be construed to limit the presentinvention or otherwise to exclude any such other embodiments,adaptations, variations, modifications and equivalent arrangements, thepresent invention being limited only by the claims appended hereto andthe equivalents thereof.

For example, those skilled in the art now also will recognize thatmethods of network formation other than the described top-down andbottom-up processes may be used to propagate a Class-Based Network basedon a multi-level hierarchy by the Wireless Reader Tags. For example, amiddle-outward approach or star configuration may be used to propagatethe hierarchical network.

Also, for purposes of describing preferred embodiments of the presentinvention, it has been assumed herein that each WRT Class has more thanone member. Otherwise, the sole member of the WRT Class communicatesdirectly with a Gateway. However, this scenario is contemplated withinthe scope of the present invention.

Furthermore, while each Wireless Reader Tag has been described asbelonging to a particular WRT Class, class membership for each WirelessReader Tag need not necessarily be exclusive, and a Wireless Reader Tagtherefore may belong to more than one WRT Class as desired in anyparticular application of the present invention. Moreover, while eachWRT Class has been described as reading a particular WT Class associatedtherewith, each Wireless Reader Tag may read Wireless Tags associatedwith different WRT Classes, as desired in the asset-trackingapplication.

With regard to the distinction between Wireless Reader Tags and WirelessTags, it is noted that each Wireless Reader Tag includes thecapabilities of each Wireless Tag and, therefore, it is contemplatedwithin the scope of the present invention that each Wireless Tag of thepresent invention could be replaced with a Wireless Reader Tag.

Furthermore, if a Wireless Tag is passive, which is contemplated withinthe scope of the present invention, then it is believed that theWireless Tag currently maintains therein only its unique WT ID. Beingpassive, no other information is maintained in the Wireless Tag. In thiscase, an associated Wireless Reader Tag maintains the identification ofits WT Class in memory as indexed by the respective WT ID of the passiveWireless Tag. Any other information, if maintained, also is stored inthe Wireless Reader Tag and indexed by WT ID, where appropriate. Ofcourse, in this scenario, any broadcast generally is answered by eachpassive Wireless Tag that is within broadcast range and, hence, suchimplementation of passive Wireless Tags, while within the scope of thepresent invention, is not preferred.

Finally, from the foregoing it should be apparent to and understood bythe Ordinary Artisan that, as used in the above description and in someof the incorporated references, such as U.S. Pat. No. 6,745,027 andapplication publication no. US 2005/0093703 A1, a “class-based” networkrepresents a network, nodes of which (and specifically, the datacommunication devices of the nodes of which) share a common “class”designation, which class designation in such references isrepresentative of an asset class. The asset class, in turn, represents agrouping of assets—whether the same or different—that share something incommon, such as an attribute, characteristic, relation, or behavior, andeach asset comprises a person or thing that is desired to be tracked ormonitored.

For example, with respect to a person, an asset may be an employee, ateam member, a law enforcement officer, or a member of the military.With respect to a thing or article, an asset may be, for example, agood, product, package, item, vehicle, warehoused material, baggage,passenger luggage, shipping container, belonging, commodity, effect,resource, or merchandise.

The data communication devices of the class-based networks also aredisclosed as being low power radio frequency (LPRF) devices, and eachdevice is disclosed as preferably including a standards based radio suchas, for example, a Bluetooth radio. Each data communication devicefurther is disclosed as preferably including memory for storingsensor-acquired data.

As will be further disclosed to and understood by the Ordinary Artisan,a class-based network is a network which nodes comprise datacommunication devices that share a common designation, and which networkis formed based on such common designation. As used herein, a networkwhich nodes comprise data communication devices that share a commondesignation, and which network is formed based on such commondesignation, is considered to be a “common designation” network. In aclass-based network, the common designation of the network is the classdesignation, and a class-based network therefore is representative of acommon designation network.

A remote sensor interface (RSI) network as used herein and in some ofthe incorporated references represents a network, nodes of which (andspecifically, the data communication devices of the nodes of which) eachare disposed in electronic communication with one or more sensors foracquiring data there from. The RSI network may be a class-based network,in which case the nodes also share a common class designationrepresentative of an asset class. For instance, the embodiments of theclass-based networks described above, and those described in U.S. Pat.No. 6,745,027 and in application publication no. US 2005/0093703 A1,each comprises an RSI network when the data communication devices of thenodes include sensor-acquired information obtained from associatedsensors. The sensors may be temperature and humidity sensors, forexample, for detecting the temperature and humidity relative to an assetbeing tracked or monitored, with the sensor-acquired information beingcommunicated back to an application server upon acquisition of the databy the sensor or at a predetermined time, as desired.

Additionally or alternatively, the nodes of an RSI network may share acommon designation other than a class designation. For instance, an RSInetwork may include data communication devices that interface withcertain types of sensors, and the data communication devices may share acommon designation that is representative of such sensors. The commondesignation of the RSI network in this case is not necessarilyrepresentative of an asset to be tracked or monitored by such sensors,although it may be. For instance, the sensors may include, for example,cameras and microphones. Speakers and video displays also may beassociated with the data communication devices for providing over theRSI network two-way audio and/or visual communications such as, forexample, video conferencing. In preferred embodiments in which the datacommunication devices include Bluetooth radios, the audiovisual data canbe sent over TCP/IP links similar to VoIP communications.

1. A method for monitoring a container having at least one RFID deviceinterior thereto, said method comprising: providing an RFID deviceinterior to a container, the RFID device periodically transmittingmessages; wherein each of the messages includes information uniquelyidentifying the RFID device, and wherein ones of the messages that aretransmitted when the container is closed are substantially attenuated bythe container, and wherein ones of the messages that are transmittedwhen an opening in the container is open are not substantiallyattenuated by the container; receiving messages transmitted by the RFIDdevice interior the container by a receiving device exterior thecontainer; whereby ones of the messages that are transmitted when thecontainer is closed are substantially attenuated and/or are not receivedby the receiving device, and wherein ones of the messages that aretransmitted when the container is tampered with and/or when the openingof the container is open are received by the receiving device; anddetermining from the messages received from the RFID device whether theopening of the container has or has not been opened and/or the containerhas been tampered with, whereby a container having an RFID devicetherein is monitored for being opened and/or tampered with.
 2. A methodfor monitoring a container having at least one RFID device interiorthereto, said method comprising: providing an RFID device interior to acontainer, the RFID device periodically transmitting messages, whereineach of the messages includes information uniquely identifying the RFIDdevice; receiving messages transmitted by the RFID device interior thecontainer by a receiving device exterior the container; and determiningfrom the messages received from the RFID device status changes of thecontainer; whereby a container having an RFID device therein ismonitored.
 3. The method of claim 2, wherein ones of the messages thatare transmitted when the container is closed are substantiallyattenuated by the container, and wherein ones of the messages that aretransmitted when an opening in the container is open are notsubstantially attenuated by the container.
 4. The method of claim 2,wherein ones of the messages that are transmitted when a status changeoccurs are received by the receiving device.